Fwiw, before deciding whether or not to buy it, I used the DST Compressor 8-iron at a golf store indoor hitting net to see if it does what it advertises. I hit several shanks initially but quickly figured out why: I often stall out at impact and don't continue to turn my hips, and for me the club tends to get out away from my body and moves toward the ball, thus hitting the ball toward the heal (note: I never shank a ball when I play or practice). After a few swings with the Compressor I realized I have to keep turning the hips in order to keep the handle and club close to my body, something I'm well aware of but have a bad habit of getting "ball bound" at impact.
For this insight alone it was worth trying it out, yet I came to the conclusion that the "lag stick" training aid - much cheaper (or just putting an alignment rod in or along your club shaft) accomplishes the same thing. If your hip turn stalls out at impact on a full swing, or you flip your wrists on a chip shot, the lag stick or alignment rod will hit you in your side (left side for righties). If you keep your lead wrist flat at impact it forces you to continue to turn, especially useful when chipping. I don't care about lag per se but I do want to have my hands leading the club head coming into at impact in order to compress the ball (while avoiding "hitting down" on the ball) and the best way for me to get that is having a flat left wrist along with continuing an aggressive hip turn (opening the hips) to the finish, not with holding off or attempting to retain lag, that takes incredible timing. Also, for your irons and woods get shafts with the proper stiffness or flex :)