C.R. LAURENCE J0SB CRL "J0" Type Offset Arm Assembly Replacement Vinyl Slide Block. This CRL "J0" Slide Block Replacement Package is designed to replace the worn or damaged vinyl slide block used on "J0" Offset Arm Assembly 7/8" (22 mm) top rail depth slide-track. Replacement "E" clip is included to secure the block. Sold individually.. Part Numbers Variations: J0SB