Crosby® McKissick 4-1/2" Sheave Block w/ Shackle - 3/8"-1/2" wireCrosby McKissick 4. 5" Snatch Block with Shackle 3 8" to 1 2" Wire Rope The Crosby McKissick 4 1 2" Sheave Snatch Block with Shackle is built for reliable load redirection, lifting, and tensioning in a variety of rigging environments. Designed for use with 3 8" to 1 2" wire rope, this Type 419 snatch block supports a 4 ton working load limit and includes a forged steel swivel shackle for secure, stable attachment. A 4: 1 safety factor ensures