This is a A-18311018SW Ref B-Spring-2 Reqd PN: 18311018SWMain Description As Following : A-18311018SW Ref B-Spring-2 Reqd P.N: 18311018SW A-18311018SW Ref B-Spring-2 Reqd P.N: 18311018SW Stocked As: A-80A80 Found in Section & Models : Miscellaneous > Miscellaneous, Sidewinder ROTARY CUTTER: VARIOUS MODELS Associated Items : New Also This is An Aftermarket Product And : Inside Diameter: 2.88" Outside Diameter: 4.725"