Check the listing for details. Karella - Shaft Lock System - 1,000 Rubber Rings With Tool - 2BA Thread. Condition: New. Listed at 79.30 USD. The Shaft Lock System prevents the shaft from coming loose or twisting out of the barrel when throwing. The sturdy rubber rings are pushed onto the shaft thread using a special aluminum tool. These mini rubber rings offer a secure hold for all common shafts with 2BA aluminum threads. Features: Material: Rubber rings and aluminum tool Color: Black Ring diameter: approx. 4 mm Properties: Prevents the shafts from coming loose: Secure hold when throwing Easy to use: With special aluminum tool Universally applicable: For all common shafts with aluminum thread 2BA Technical data: Feature Description Material (rings) Rubber Material (tool) Aluminum Ring diameter approx. 4 mm Scope of delivery: 1000 x rubber rings (O-rings) 1 x aluminum tool Attention! Not suitable for children under 3 years. Dang.