Stan OnneX Thumb Release This release features specialized trigger mechanisms made from enhanced and hardened 440C stainless steel, fully adjustable trigger tension and travel and adjustable thumb knobs, thumb post extensions and finger pieces. In addition to this, all handle sizes and release points remaining the same no matter the firing mechanism. The Thumb and Resistance models have the incorporated Sping-loaded string keeper for a fst hook up to the D-Loop INCLUDED IN THE PACKAGE: Interchangeable 3 or 4 finger pieces 2 different thumb barrel extension lengths made from Stainless Steel 2 thumb barrels, smal and a large both made from stainless steel