Our ring clamp is Swiss style and made primarily of aluminum. The jaws are leather lined (the preferred material for holding rings). The handle features a cushion grip with excellent properties. It is very slip resistant but not too soft. The jaws are "pulled" closed by the knob at the lower end, which cannot slip as conventional wooden ring clamps do. Maximum opening is just over 1/4" (7.50mm). Length 6 3/4" (15mm).