This probably the easiest blade to measure and determine, as there are fewer variables. Bore size or shaft size and width from center to outer edge times two. Pitch is generally 28 degrees or 33 degrees with most running clockwise... although there are several that run opposite but are rare. Lau 60743401 2-Blade Fan 36degree Pitch 1/2" Bore 14" $22.53 Lau 60652101 2-Blade 1/2" Bore 33d Pitch CCW 18" $27.77 Lau 60772601 2-Blade Fan 28d Pitch 1/2" Bore CCW 20" $28.25 Lau 60814201 2-Blade Fan 27d Pitch 1/2" Bore CCW 22" $37.36 Lau 60772501 2-Blade Fan 28d Pitch 1/2" Bore CCW 18" $27.77 Lau 60772701 2-Blade Fan 16d Pitch 1/2" Bore CCW 22" $31.71 Lau 60772801 2-Blade Fan 27d Pitch 1/2" Bore CCW 24" $32.84 Let us help you through the selection process. Value ac is a proud distributor of Hart and cooley registers, air diffusers, vent covers, and air conditioning vents. We can special order anything you need. Please call us at 1-888-242-7725 Toll Free for a quote. We want to earn your trust! Floor Registers and Vent Covers Blog