40 A 42 Tooth Plate Style Sprocket CNC Machined for the Peerless 100 Series 1" and 3/4" Differential. 
It has the 4 bolt hole pattern drilled and has a 2-1/8" ID to match the hub. 
Use # 40 Chain 1/2" pitch x 5/16" width. 
Black Finish is standard.
Actual weight is:  2 lb 5 oz