RSMRS500 - Fits these springs:MRP Enduro SL and Progressive.Fits these shocks:Rock Shox Kage, Vivid and Super Deluxe Coil shocks with a maximum of 65mm of strokeMRP Hazzard shocks with 63 or 65mm of stroke to be used with spring rates under 425 lb/inMRP Hazzard shocks with 57.5 or 60mm of stroke to be used with spring rates under 375 lb/inDimensions:Short spacer is 4mm, tall spacer is 8mm (overall effective length is 12mm when installed)Spring seat external diameter is 1.475"/ 37.5mm, shock seat / preload collar seat internal diameter is 1.45" / 36.8mmRSMRS501 - Fits these springs:MRP Standard Steel // Fox SLS and "standard" steel models.Fits these shocks:MRP Hazzard and Raze V2Rock Shox Kage, Vivid and Super Deluxe CoilDimensions:Short spacer is 4mm, tall spacer is 8mm (overall effective length is 12mm when installed)Spring seat external diameter is 1.38"/ 35.1mm, shock seat / preload collar seat internal diameter is 1.45" / 36.8mmRSMRS502 - Fits these springs:MRP Enduro SL and ProgressiveFits these shocks:MRP Raze (V1, 2018 and earlier)Fox Van, DHX, RC4, and DHX2 shocks with a maximum of 65mm of strokeDimensions:Short spacer is 4mm, tall spacer is 8mm (overall effective length is 12mm when installed)Spring seat external diameter is 1.475"/ 37.5mm, shock seat / preload collar seat internal diameter is 1.35" / 34.3mmRSMRS505 - Fits these springs:MRP Enduro SL and ProgressiveFits these shocks:Cane Creek Double Barrel shocks with a maximum of 65mm of strokeDVO Jade shocks with a maximum of 65mm of strokeOhlins TTX shocks with a maximum of 65mm of strokeMarzocchi Roco and Moto shocks with a maximum of 65mm of strokeX-Fusion Vector shocks with a maximum of 65mm of strokeDimensions:Short spacer is 4mm, tall spacer is 8mm (overall effective length is 12mm when installed)Spring seat external diameter is 1.475"/ 37.5mm, shock seat / preload collar seat internal diameter is 1.43" / 36.3mm