Ping's successful line of G-series woods and irons have focused on maximum forgiveness for all players, but its i-series has been geared specifically to players who place a premium on manipulating the club to control ballflight.
The i20 line of driver, fairway wood, hybrid and irons attempts to satisfy that audience by utilizing a series of designs that focus on keeping the center of gravity closer to the hosel axis to improve a player's ability to manipulate the clubhead during the swing. It all comes with a renewed emphasis on forgiveness, too, says Ping's director of product design Brad Schweigert. That's especially true on the cheap Ping i20 irons, which feature a tungsten toe weight to improve clubhead stability and a progressive shape (larger long irons, smaller short irons) in an effort to give the golfer more control.
According to Marty and PING, the i20s have a couple more degrees of bounce with the addition of a little smaller camber radius from the front to back. This makes it more rounded from front to back, it also helps the playability of the leading edge. With the i20s lower the center of gravity, the clubhead wants to deflect down into the ground when impacting the ball, so these design changes allow the club to glide through the ground, taking nice shallow divots.
"What we were able to do was improve forgiveness and lower the CG, but we also put the CG in a location that makes the clubs feel like the blades these players grew up with," Schweigert says. I personally don't like thin top lines, like to see some "meat" behind the ball. As with the offset, the i20s are in between a game improvement club's "chunkiness" and muscle back skinny.
The cheap Ping i20 irons [http://www.salegolfclubs.co.uk/Cheap-Ping-I20-Irons-price-1146.html] are noticeably longer heel to toe in the long irons, gradually decreasing in size to the short irons and wedges. This time around, PING made the top rail thicker in the long irons transitioning towards a thinner top line in the 7-W, dramatically increasing the MOI where golfers need it most.
To sum up, the long i20 irons are super easy to hit and I think that is where the pull cavity design is a real winner. At address with the 4 iron you can see part of the under cavity. This is just part of the design of the pull cavity. I don't mind it, just lets you know there a little extra love to help you hit a towering long iron.
Source from: [http://www.salegolfclubs.co.uk/article-402-Ping+I20+Irons+Pack+in+a+lot+of+new+Design+Tweaks.html]