Credit: USGA

Phil Mickelson hinted following the second round of the Shell Houston Open that he was going to test a "special club" the week before the Masters.

"We have a special club we're making that I'll be hitting on Monday," Mickelson said. "So, we'll see."

Mickelson and Callaway wouldn't divulge the details surrounding the club, but according to Golfweek's David Dusek, the USGA's Conforming Driver List gave an indication of what the three-time Masters winner could have up his sleeve.

Listed in the USGA's database was an X-Hot wood called "Phrankenwood." The club doesn't have a listed loft and the pictures don't give you an idea if the club is another driving 3-wood -- like the recently released 3Deep model Mickelson started using at the Northern Trust Open -- or a driver with a twist.

Regardless, it looks Phrankenwood could be Mickelson's "special club." No word yet if Mickelson will put it in play this week at the Masters, but there's a good chance he'll be testing it early in the week to see if it's worth putting in the bag for the first round.

Phil Mickelson has two Callaway 3-woods in the bag this week at Redstone. (Halleran/Getty Images)

By Jonathan Wall, PGATOUR.COM Equipment Insider

The Shell Houston Open has been more than just a final Masters tuneup for Phil Mickelson over the years; it's also turned into an equipment testing ground of sorts for the four-time major winner.

Mickelson famously used two Callaway FT-3 to win the 2006 Masters, but before he brought the drivers to Augusta National, he tested them out at the Shell Houston Open.

While Friday's equipment adjustment didn't rival the dual drivers, Mickelson's decision to drop his Callaway RAZR Fit Xtreme driver — the same driver he used to win the Waste Management Phoenix Open — and use a setup that included an X Hot 3Deep 3-wood and two additional fairway woods was intriguing.

Callaway unveiled X Hot 3Deep at the beginning of the week — a taller-faced version of the X Hot Pro fairway wood that, for Mickelson, is almost as long as his driver and gives him the ability to work the ball both ways with ease.

Even though Mickelson struggled for much for the second round and nearly missed out on the weekend, he was able to string together three straight birdies starting on the 11th hole to make the cut on the number at 1 under.

With two additional rounds to work on his game before the Masters, the big question is if Mickelson will continue with 3Deep as the longest club in his bag for the rest of the week.

"We have a special club we're making that I'll be hitting on Monday," he said after the round. "So, we'll see."

Even if Mickelson decides to put a second 3Deep fairway wood or something else in play, there's no question the new 3-wood has given Mickelson a new-found confidence off the tee — something he could use with the Masters less than two weeks away.

"I have a chance now when I show up," he said. "I'm not searching. I'm not trying to find it. I know what it is I'm trying to do and the feelings I'm trying to create to hit certain shots. I have a chance to shoot a low round."

Phil Mickelson switched to an Odyssey Versa #9 WBW putter this week. (Callaway Golf)

By Jonathan Wall, PGATOUR.COM Equipment Insider

Phil Mickelson isn't exactly struggling with the putter — he's currently ranked 25th in strokes gained-putting this season — but that didn't stop the 41-time PGA TOUR winner from shelving his Odyssey Black Series Tour Design #9 for an Odyssey Versa #9 WBW (white-black-white) at the Arnold Palmer Invitational presented by MasterCard.

Over the first three months of the season, Mickelson has bounced between the two putters, using the Versa #9 at the Northern Trust Open before switching back to the Odyssey Black Series Tour Design #9 at the WGC-Cadillac Championship.

Mickelson decided to go back to the Versa #9 after making a couple adjustments to the putter with Odyssey's principal designer Austie Rollinson last week. Mickelson added a custom sight line to the putter — similar to the sight line he had on his Black Series Tour Design #9 — and went with a new SuperStroke "Slim 55" grip.

Looking for a firmer grip, Mickelson had it added to one of the putters Rollinson built for him to test out. After working with it during his off week, Mickelson felt comfortable enough to put it in the bag.

Phil Mickelson arrived with Riviera with two new Callaway woods in the bag.

By Jonathan Wall, PGATOUR.COM Equipment Insider

PACIFIC PALISADES, Calif. — Two weeks after Phil Mickelson put a Callaway RAZR Fit Xtreme driver in play at the Waste Management Phoenix Open and won by four shots, the four-time major winner arrived at the Northern Trust Open with two new Callaway woods in the bag on Wednesday -- an X Hot Prototype 3-wood and a RAZR Fit Xtreme 5-wood.

Mickelson started working with the X Hot Prototype 3-wood two weeks ago during the second round of the Farmers Insurance Open but went back to his TaylorMade RocketBallz 13-degree (bent to 11.5) shortly thereafter.

After working with the fairway wood over the last few weeks, including on Tuesday at the Ely Callaway Performance Center, he decided to put it back in the bag.

The RAZR Fit Xtreme 5-wood is a brand new addition this week and would replace the Titleist 980F 5-wood Mickelson's been playing of late.

Assuming Mickelson puts both fairway woods in play on Thursday, he would have 13 Callaway clubs in the bag to go along with an Odyssey putter.

By Jonathan Wall, PGATOUR.COM Equipment Insider

Dr. Alan Hocknell, Callaway's Senior VP, Research & Development, played a critical role in helping Phil Mickelson gain some much-needed confidence off the tee at the Waste Management Phoenix Open.

In the latest edition of "Callaway Talks," Hocknell spent some time talking with Harry Arnett, Callaway's SVP, Marketing, about what the time and effort that went into creating Mickelson's new driver. 

As Hocknell noted, Mickelson had some specific driver requirements that had to be met. After working with Mickelson for "a while" on the new driver, the Research & Development was able to design a RAZR Fit Xtreme that met the four-time major winner's specifications.

The end result was a driver that helped Mickelson win his third Waste Management Phoenix Open title.

By Jonathan Wall, PGATOUR.COM Equipment Insider

Every club in Phil Mickelson's bag was working at the Waste Management Phoenix Open, but it was his new Callaway RAZR Fit Xtreme driver that gained the most attention during his four-shot win on Sunday in Scottsdale, Ariz.

Mickelson, who switched from a RAZR Hawk Tour driver to one of Callaway's latest driver offerings on Tuesday, following a productive range session, averaged 298 yards off the tee for the week, including a 358-yard drive during the second round.

“This driver spins so low that I can have more loft on the club, making it easier to hit," Mickelson said. "This has got to be good for every player I would think, but it sure as heck is good for me. And by having it be a low-spin driver with enough loft, and because it's that RAZR Fit Xtreme where you can fit it, I was able to get it dialed in to where it goes straight. But I'm able to make the same golf swing as my irons so you'll see me extend down the target line, you won't see this kind of tilt because it's not enough loft to get up and it's not low enough spin to not float, and it has been — it really could be a revolutionary club for me."

The 9.5-degree driver has an actual loft of 8.1-degrees with 5 grams in the toe and 3 grams in the heel. The 45-inch shaft is a Mitsubishi Rayon Fubuki K. 059 prototype model 70X.

Mickelson also made one other adjustment to his bag prior to the start of the first round, replacing the Callaway X Hot Prototype 3-wood he put in play during the second round of the Farmers Insurance Open with the TaylorMade RocketBallz 3-wood he's been gaming since last November.

Phil Mickelson's bag:

Driver: Callaway RAZR Fit Xtreme Driver (9.5 degrees) with a Mitsubishi Rayon Fubuki K. 059 prototype model 70X shaft
3-wood: TaylorMade RocketBallz (13-degree, bent to 11.5 degrees) with Mitsubishi Rayon Fubuki K 80X prototype shaft
5-wood: Titleist 980F 5-wood (17-degree) with a Graphite Design PM 902 shaft
Irons (4-PW): Callaway RAZR X Muscleback Irons with KBS Tour shafts
Wedges: Callaway JAWS Wedges (52 degrees, 60 degrees, 64 degrees)
Putter: Odyssey Black Series Tour Design #9
Ball: Callaway HEXBlack Tour golf ball

(Miralle/Getty Images)

By Jonathan Wall, PGATOUR.COM Equipment Insider

SCOTTSDALE, Ariz. — The equipment changes keep coming for Phil Mickelson. On Wednesday at the Waste Management Phoenix Open Pro-Am, the four-time major winner showed up with a new Callaway RAZR Fit Xtreme driver in the bag.

After using a 9.5-degree RAZR Fit last year to win the AT&T Pebble Beach National Pro Am, Mickelson decided to switch things up and put a RAZR Hawk Tour driver in the bag.

The RAZR Hawk Tour was still in the bag for the first two events of 2013, but according to Mickelson, a recent session with the new RAZR Fit Xtreme a couple days before the start of the Waste Management Phoenix Open led him to believe it was time to switch to one of Callaway's latest driver offerings.

"This RAZR Fit Xtreme is one of the hottest driver I've seen as far as keeping the spin down, easy to hit, and I just gave it a try here the other day, and I hit it significantly better than what I've been hitting," Mickelson said on Wednesday. "I'm excited about having it this week, just driving the ball better."

Over the first month of the season, Mickelson has tried out a couple new clubs, including a Versa #9 putter at the Humana Challenge, and a Callaway X Hot Prototype fairway wood at the Farmers Insurance Open. 

By Jonathan Wall, PGATOUR.COM Equipment Insider

Here are some equipment news and notes from around the golf world this weekend:

Lee Westwood tests out new Ping G25 driver

David Toms puts Cleveland tour-only prototype irons in play at Humana Challenge