Jobu 50mm QR Clamp All Metal QRR-1 Arca Compat for Tripod Head All metal construction. Knob is metal, contains no plastic or rubber Made in Canada Will fit many brands of ball heads including most Bogen models etc. Precisely engineered to exact Arca Standard Includes: Clamp, (1x) 1/4"-20 SAE bolt, (2x) 6mm Metric bolt (2 lengths)