The Berkeley Flashmer Swivel combines a brass body with stainless steel rings to absorb rotation between two sections of the rig. Nine sizes cover the range from No. 6 to 3/0. The rated strength ranges from 22 kg for No. 6 to 216 kg for 3/0. Size No. 3 is rated at 67 kg, No. 1/0 at 134 kg, and No. 2/0 at 212 kg. Each pack contains 100 swivels of the same size.