All spearfishermen eventually when they become experts, personalize their equipment, one of the first things to customize are the slings, seeking for a solution that will give better performances. -Calculate sling length from barrel length, head width, wishbone length and enlogation factor.-Get information about number of pump strokes and pressure for major air guns (Omer, Cressi, Mares,...)KWArbalete, apnea, pescasub, spearfishing, sub, diving, spearfish, pesca, fishing, roller, apnea, Cressi, Omer, podvodni ribolov, ribolov