Product Features:
Stainless Steel Base, Head post & Hub
Roller are not ball bearing so they will not have any issues that come with ball bearing rollers
Side-plates: UV-stabilized with reinforced nylon composite for maximum protection 
Block Connection: Base Mounting
Becket: No
Mounting screws are NOT included
Specifications:
Sheave Diameter: 3.54" (90mm)
Max. Line (Rope) Diameter: 0.78" (20mm)
Max. Working Load (MWL): 9920lb (4500kg) 
Breaking Load: 4960lb (2250kg) 
Weight: 3lb 1oz (1388gr)
Base plate: 6.5x4.7" (165x120mm)
Mounting holes on center: Short side:3.7" (94mm). Long-side: 5.5" (140mm)