Exclusive "form-through" shank design prevents coupling pull out and really stands up to those tough, big-bore cleaning jobs. Our famous bronze, stainless steel and nylon cleaning brushes with heavy-duty, 10-32 thread couplings that won't pull out no matter how hard you clean. Made for use with the Dewey Large-Bore Coated Rods. Mfg: Brownells SPECS: Bristles: Phosphor Bronze. Shank: Steel, looped and wound. 2-7/8" (7.3cm) OAL, 10-32 thread.