“Added RIBCOR bracing (stiffening beams behind the face toward heel/toe) for tighter dispersion and speed, plus a fluted hosel and 360-degree undercut. A strong rung-1 gamer for the everyday player; distance-oriented lofts in the same family as the M2/M6.”

The M4 replaced the M2 as TaylorMade's mainstream game-improvement iron for 2018, built around a new RIBCOR chassis: two internal bracing beams run behind the face toward the heel and toe, stiffening those zones so more energy returns to the ball on off-center hits instead of dissipating into head flex. TaylorMade paired that with a 1.5mm face (its thinnest GI iron face at the time), a thin-walled Speed Pocket for low-face strikes, tungsten sole weighting, and a fluted hosel plus 360-degree undercut cavity for sound. It tested noticeably longer than both the M2 and the tour-oriented M3 alongside it, with TaylorMade citing a 24% MOI gain over the M2. It won a 2018 Golf Digest Hot List gold medal and was replaced by the M5/M6 irons in 2019.

A well-reviewed, high-volume annual-refresh iron with no lasting mystique: it slotted for exactly one model year between the M2 and the 2019 M5/M6 irons on TaylorMade's yearly product cycle, generated strong trade press at launch (Golf Digest Hot List gold, favorable ClubTest and Golf Monthly reviews) but no forum-legend afterlife, scarcity, or tour mythology of its own. It is remembered as a solid iteration, not sought out.

Mid-to-high handicappers wanting distance and easy launch from a conventional iron shape; TaylorMade's own positioning was 'speed and forgiveness' for players trading down from blades or players' cavities. Better ball-strikers wanting workability or a compact look should look at the M3 from the same year instead; the M4's strong, distance-tuned lofts (PW around 43 degrees) also mean gapping needs a fitter's attention against a mixed bag.

• Won a gold medal on the 2018 Golf Digest Hot List.
• RIBCOR bracing (two internal beams behind the face, heel and toe) was the headline new tech, shared with the tour-flavored M3 released the same year.
• TaylorMade claimed a 1.5mm face — the thinnest face on a TaylorMade GI iron to that point — plus tungsten sole weighting for a lower CG.
• TaylorMade's own stability testing claimed a 24% MOI improvement over the outgoing M2 iron.
• Stock steel shaft was True Temper XP 100, with a graphite option also offered; MSRP was $799 for a 7-piece steel set.
• Replaced the M2 in TaylorMade's lineup and was itself replaced after a single year by the 2019 M5/M6 irons.

Launched alongside the tour-oriented M3 as TaylorMade's 2018 two-tier iron strategy, competing directly with Callaway's Rogue and Ping's G700/G400 game-improvement irons. It was replaced after one year by the Speed Bridge-equipped M5/M6 irons (2019), and that generation gave way to P790/SIM-era irons by 2020 — TaylorMade's fastest iron refresh cadence of the era.

A 7-8 year old mainstream GI iron with no collector premium: complete steel sets (4/5-PW or AW) typically sell for roughly $130-$260 private-party in 2026 depending on shaft condition and grooves, with reconditioned-retail listings (2nd Swing, Golf Avenue) running higher for graded/warrantied examples. It is a serviceable, cheap gamer or loaner set, not an investment.