Unbonded Capping is a safe, accurate and economical alternative to the use of hot sulfur capping compound for compressive strength tests of concrete specimens. Steel Retainer Rings hold Tough 1/2in, (12.7mm) thick neoprene pads at each end of the concrete test cylinder to distribute compressive load forces evenly. The Retainer Rings are permanent with normal care and the Neoprene Pads are reusable 100 times or more with qualification testing by user. Neoprene Pads and Steel Retainers are sold separately. Retainers and Pads for 2in specimens are also suitable for use on 2-1/8in diameter rock cores.