Made by Rob Allen! Need we say anything else? No, but we will. Blue bands are 16mm (5/8") diameter and made for the Tuna series guns by Rob Allen, but also can be used on any speargun where you need a quality, blue band. Green bands are 14mm (9/16") diameter and made for the Snapper series guns by Rob Allen, and any other speargun where you need a quality, green band. These bands are sized for the Rob Allen gun they belong on, so if you need bands for a 100cm gun, you buy the 100cm band of the corresponding color. Easy!