Callaway Big Bertha irons unveiled

The new Callaway Big Bertha irons come with the promise of explosive distance

The new Callaway Big Bertha irons, which come with the promise of explosive distance, have been unveiled.

The main technological innovation comes in the form of a 360 face cup, which Callaway says makes the irons up to two clubs longer than previous models.

This new design has been employed previously in fairway woods and hybrids, but Dr Alan Hocknell - Callaway's head of R&D - and his team have now transferred that across to irons for the first time through a two-piece iron construction.

The Cup technology in the Callaway Big Bertha irons generates faster ball speeds across the entire face while also improving the collision time - the time the ball takes to leave the face at impact.

Callaway says the centre of the new face delivers 3mph more ball speed than recent models, while variable face thickness means off-centre hits also come off the face, on average, 2.5mph faster for more distance.

This springy effect is designed to deliver distance that Callaway claims has never been seen before in an iron.

"This is the first time a face cup has been put into an iron," Hocknell told GM. "We've also introduced a new heat treatment process to the two 17-4 stainless steel pieces to improve the strength of face, which is needed now it's thinner and more flexible."

What's more, the centre of gravity is low and forward in the Callaway Big Bertha irons, allowing engineers to offer a higher moment of inertia, contributing to impressive forgiveness and ball speed.

As well as creating a forgiving distance iron for game-improvers, Callaway wanted to produce a model that would also offer some workability for the slightly better players.

As such, the sole width becomes progressively narrower as the set moves from long to short irons.

The Callaway Big Bertha irons come in two shaft options - True Temper Speed Step BO and a new UST Recoil Graphite - and are available from 4-SW (54 degrees).

The seven-iron set with the steel shafts comes with an RRP of £699, while the graphite version will set you back £899.