These narrow 114 link chains are compatible with all freewheels and cassette systems. Both chains use hardened roller surfaces and side plates as well as hollow link pins making it the second lightest competition chain in the world, at only 277 grams. The pins are 7.33mm long with a 3.5mm hollow inner diameter, and a 4.85mm outer diameter. 13 links at one end use the traditional solid pins, so the chain can be worked on with all standard chain tools. Regina has an improved riveting process that provides greater strength and reliability. The roller plates have a slight camber effected by bending the top and bottom of each roller plate outward. Made in Italy. The 50 SL chain has Black link plates, roller plates, and pins. The 50 SL America has nickel plated parts, giving it a Silver color.Regina has vacated the bicycle chain market, in the US and sells only motorcycle chains. No longer made we sold each of these for $24.99