Harken 57mm Aluminum Double Footblock

Item #


Product Description

Harken Black Magic Footblock


Sheave Ø (mm)57 mm

Sheave Ø (in)2 1/4 in

Length (mm)84 mm

Length (in)3 5/16 in

Height (mm)46 mm

Height (in)1 13/16 in

Weight (g)215 g

Weight (oz)7.6 oz

Maximum line Ø (mm)12 mm

Maximum line Ø (in)7/16 in

Maximum working load (kg)750 kg

Maximum working load (lb)1650 lb

Breaking load (kg)1500 kg

Breaking load (lb)3300 lb

Number of fasteners4

Fasteners (mm)6 FH mm

Fasteners (in)1/4 FH in

A (mm)7 mm

A (in)9/32 in

B (mm)23 mm

B (in)7/8 in

C (mm)52 mm

C (in)2 1/32 in

D (mm)16 mm

D (in)5/8 in

E (mm)58 mm

E (in)2 9/32 in

F (mm)84 mm

F (in)3 5/16 in

G (mm)12 mm

G (in)15/32 in


The entire line of Black Magic® AirBlocks® has been redesigned with a sleek new look. Their unique, performance-packed engineering remains exactly the same.

Carrying some of the highest loads imposed by running rigging, these strong, lightweight blocks feature Torlon® roller bearings housed in a center cage. Rollers stay parallel for low-friction efficiency. Sculpted hardcoat-anodized aluminum sideplates protect sideload ball bearings. Dissimilar metals are isolated to minimize corrosion. Blocks are easily disassembled with a single hex wrench.

Either metric or imperial flathead fasteners may be used for mounting and are not exposed.