This is the OMER MicroSpeed Slide Ring Line Retainer for 6.75MM shaft Features: Weight 0.01 lbs Dimensions 1 × 1 in Slide ring and line retainer in one. This is the stock slide ring for the OMER Airbalete, but it could also be used for any pneumatic speargun with a 9/32/7mm shaft or 6,75mm.