Titleist irons are an excellent example of evolution rather than revolution. Titleist sticks to their strict two-year launch cycle, with new releases consistently improving and making marginal gains on the previous model.
As a company, Acushnet (Titleist's owners) aim to make serious clubs for serious golfers - and this is back up by their vast use across the PGA Tour and European Tour. Leading the way are Major winners Justin Thomas, Jordan Spieth, and Adam Scott. Their confidence in the brand and its equipment is backed up by the 14-club deals they all sign, plus the Pro V1 ball.
When browsing second-hand Titleist irons, they make it very easy as Titleist continued to use the same model name (AP1, AP2, CB, MB), just changing the "edition" (710, 712, 714, etc.). Until their new range in 2019, but we'll come on to that later.
Working from the bottom up, Titleist is one of the few brands continuing to make a pure blade - their MB model. The MB stands for Muscle Back and is designed for the purest of ball strikers with a huge emphasis put on feel rather than forgiveness. Beautiful to look at but extremely difficult to hit.
Next in line is the CB or "Cavity Back". These irons will look a little more familiar as they start to feature some forgiveness technology built into the back of the clubhead. This does not suddenly make them a game improvement set of irons - they're still a performance club for the better players, just with a small bit of help built-in on the longer irons.
The bulk of Titleist irons fall under "AP" or Advanced Performance, and the AP2 is the most played iron on Tour and a favourite of Jordan Spieth. This iron is the perfect blend of feel and forgiveness, not only for the best players in the world but amateurs too. Tungsten weighting and a large cavity provide help where it's needed, while a progressive offset and top-line inspire confidence in the scoring zone where accuracy counts.
And finally, there's the AP1 - Titleist's game improver iron set with everything you'd expect to get the best out of your game. A thick top-line, wide sole and deep cavity all help you get the ball in the air more consistently.
In 2017 Titleist introduced the AP3 which took the best bits of the AP1 and AP2 to build a performance distance iron with the look of a players iron. This confused the naming convention (going AP2, AP3, AP1) so for their 2019 release, the T-Series replaced AP.
Named the T100, T200 and T300 the new irons fit the same categories as the AP2, AP3, and AP1 did before them just in an easier to follow convention. The number relates to head size with the T100 (replacing the AP2) being the smallest and the T300 (replacing the AP1) being the biggest. Performance and technology are directly related to clubhead size as there is more space to get the technology in.
There is a final set of irons which you'll all have seen in use - the T-MB. Remember Jordan Spieth on the range at The Open? His fantastic recovery shot was with a T-MB utility iron. These irons are also available in a full set and are the pinnacle of research and development for the engineers at Titleist.