Cast iron clamp heads and steel bar construction., 24-Inch Capacity BESSEY 24 in. Capacity High-Performance Metal Fabricator's Clamp with 8 in. Throat Depth DT 2400-24 - The Home Depot Shop Fox F-clamp Heavy Duty F-Clamps | Clamps | Wilton Tools | F-Clamps - Diamond Tool Store Shop Fox Heavy Duty 24 Inch F Clamp With Wood Handle Cast iron clamp heads. Steel bar construction Long, narrow stationary head allows these clamps to reach into tight places. Upgrade your workshop with the Shop Fox D2918 24-inch heavy-duty F-clamp featuring non-marring pads, cast iron heads, and 4-3/8-inch depth for versatile clamping These Heavy-Duty F-Clamps feature quick sliding adjustment, non-marring pad protection and 4-3/8 of depth for just about any clamping requirement.