Callaway says their new Steelhead XR irons have faces close to the legal limit for springiness (set by the R&A), just like a driver.
It's the first time we've heard a manufacturer make such a claim when it comes to irons.
So it led us to ask how much more performance do you get from cup faces and speed slots in irons?
It's not quite as easy to answer as you'd think.
Looking at numbers, if we take three of our favourite 2016 irons with speed slots or cup face technology, and compare them to three 2016 irons that don't have the same tech, ball speed and distance gains are spelt out very clearly.
3 x 2016 irons with speed pockets or cup faces
Average ball speed: 131mph
Average carry distance: 189 yds
3 x 2016 irons without speed pockets or cup faces
Average ball speed: 126mph
Average carry distance: 177 yds
On average then it's clear to see TG's test pro Chris Ryan gained 5mph of ball speed and 12 yards of distance when using springy-faced 7-irons this year.
But it's not that simple.
The lofts on those six clubs vary from 28.5 to 34° (the average speed pocket 7-iron was 30°, and non-speed pocket iron 33°) – over a club's difference for what supposedly are meant to all be 7-irons.
This explains some of the difference in ball speed and carry, but most likely not all of it.
There's little doubt these funky faces consistently go further – but some of that difference is down to the stronger lofts.