The RMC Ox-Yoke Black Powder Revovler Wonder Seals - New preformed seals for sealing chambers on blackpowder revolvers to help prevent crossfires when shooting. Easy to use simply place seal over ball on end of cylinder and push it in place to expand it to make a seal , no need to smear lube or grease to prevent a crossfire. Features100 seals per containerAvailable in .36 or .44 caliberNo need to use grease or lube