Shimano RM50 solid axle rear cassette hub has 130mm spacing; this spacing was used on many early mountain bikes equipped with Shimano 6 or 7 speed. This rear hub will need a Shimano UNIGLIDE (UG) cassette, where the smallest cog screws on to the freehub body, NOT the hyperglide (HG) style cassette, which has a lockring. You can use a 6 or 7 speed UG cassette (but NOT a Dura Ace cassette). Comes with axle nuts and washers. NEW old stock!