The Nelco Turned Iron Shot Put is a solid cast iron shot that has been machine turned to different diameters and balanced for high performance throws. This shot put meets all Collegiate, International and High School Specifications.To obtain proper fitting of the shot to the ability of your athlete:1) Finger length is critical. The shot must rest on the Pad (callus) of the palm and the fingers must be up the side of the shot. Throwers with "shorter" fingers may find that the smaller diameter shot feels better at delivery & those with longer fingers may like the feel of the larger diameter.2)?The final decision is a personal choice by the thrower and you may need 2-3 diameters to fit the whole team. From a Bio-mechanical point of view, the larger shots give a greater contact area & push zone.