Quick view Otter Creek Labs Ocl M4 Collar Raw Heat Treat $43.18 Locating collar for M4 spec barrels and ops inc 12th model, AEM5 and OCM5. Made from H900 heat treated 17-4 steel with a Raw Heat Treat Gold finish.Features :Raw Heat Treat Gold Finish17-4 SteelCompatible with Ops Inc 12 model, AEM5 and OCM5 Compare Add to Cart