P18/19 Ronstan Mast Head Sheave 

Murrays Part# 56-6804

Replacement sheave for mast base on Prindle 15, 18, 18.2, 19 and Nacra 2003 and later mast head. Sheave measures 1-1/8" diameter x 3/8" wide.  Please note that this item replaces #6803 that is no longer available.

Specifications:

Diameter: 28mm - 1 1/10"
Width: 10mm - 3/8"
Hole Diameter: 7mm - 1/4"

Performance Sports Factory Part# 6804