With its new M3 and M4 irons, TaylorMade has introduced a “RibCOR” technology that’s designed to produce more speed on mishits. Before we get into what exactly that design is, let’s see why this concept is important.

COR, or coefficient of restitution, is the measure of energy transfer between two objects. For golf club manufacturers, especially when making game-improvement irons, the goal is to get COR as high as possible; this means ensuring as much energy gets transferred from the club face to the golf ball as possible during impact. Of course, the USGA sets a limit on COR of golf clubs so they can only go so far.

Many companies these days have figured out how to maximize COR on the center of the club face. Now, the game for engineers across the industry has become “how high can we make COR on shots hit off-center.” The goal obviously being to produce as much speed on off-center hits as possible, or, minimizing energy loss at impact.

TaylorMade, for its new M3 and M4 irons, has introduced RibCOR technology that uses two ribs, or beams, on the outer portions of the heel and toe as pictured below.

This provides internal support on the outer portions of the club so that the face can flex as much as possible at impact, thus retaining energy transfer from the club the golf ball. So while the center of the face may not produce more speed compared to its M1 and M2 predecessors, this design should impart more ball speed across the face. That means more forgiveness, or MOI (moment of inertia).

The RibCOR design couples with a number of familiar technologies from the company’s past including inverted cone technology, speed pockets and face slots. These are all designed for to produce higher ball speeds and more forgiveness, helping golfers who don’t hit the center of the face every time to launch the ball high and far.

As with the M1 and M2 irons they replace, the lower-numbered M3 iron has a more compact look and is designed for slightly better players, whereas the higher-numbered M4 iron is built for more distance and forgiveness, and has a larger head profile.

For more photos and discussion click here, or read below for more info on each of the offerings. Both the M3 and M4 irons will be available at retail on February 16.

Taylormade M4 irons

As the more forgiving of the two M-family offerings, TaylorMade’s M4 irons have fluted hosels, 1mm toplines, and what TaylorMade calls its “thinnest ever leading edge.” Also, along with the RibCOR technology that’s in both the M3 and M4 irons, additional mass has been placed on the toe and heel portions of the M4 irons to produce great forgiveness on off-center hits.

Overall, the M4 club heads have 24 percent higher MOI than the M2 2017 heads, according to TaylorMade, so golfers will find them to be more forgiving than their predecessors.

The M4 irons (4-LW) will come stock with either KBS Max 85 steel shafts (R and S flex), Fujikura Atmos shafts (5A, 6R, 7S), or additional custom shafts, with TM Dual Feel grips. Steel will sell for $899 per set, while graphite will sell for $999.

Taylormade M3 irons

The TaylorMade M3 irons, while housing some of the same technologies as the M4 irons, are made for those players who want a more compact shape and are looking for more trajectory control. To help achieve this look without sacrificing much by way of forgiveness, TaylorMade ha added a 15-gram tungsten weight to the soles of the M3 irons; this lowers CG in the head.

The irons have a 180-degree fluted hosel — that means it’s not as visible at address compared to the 360-degree fluted hosel in the M4 irons — to help move weight away from the heel. The irons have a thinner topline than the M1 irons they replace, according to TaylorMade, and have soles designed with more bounce for better turf interaction.

M3 sets (3-SW) come stock with either True Temper XP100 steel shafts (R300, S300), Mitsubishi’s Tensei graphite shafts (70R or 80S), or additional custom shafts, and with Lamkin UTx NC grips. M3 irons will sell for $999 with steel shafts or $1199 with graphite.

Click here for more photos and discussion on the M3 and M4 irons