These are high quality Japanese replacement chainrings made of dur-aluminum by either Sugino or SR (Sakae Ringyo).
They are made of 3.0mm aluminum plate stock that is stamp cut to shape and then turned on a lathe to cut the tooth area to width and produce the precision tapered teeth on both sides. Each of them also has the fixing mounting holes redrilled to recess the fixing bolt screw head or nut. After machining, they are anodized to prevent oxidizing. The outer chainrings do not have an anti-jam pin.
Mountain bike sizes are available in Silver or Black, (Black costs a bit more). Road racing sizes are available only in Silver. Mountain bike bolt patterns are 74mm for the inner, 110mm for the middle and outer chainring.
Road racing doubles use 130mm for both chainrings. Weights for each of the sizes are listed in the accompanying table. Available as mountain bike or road bike replacements. $ Price and Sizes Available in Catalog
Bike Pro Alloy Chainrings