The original dual chamber air spring cartridge. The patent pending design provides a near linear compression curve for a “coil-like” feel while maintaining infinite adjustability Easy dropin installation Coil like suppleness and midstroke support Builtin tunable progression or “bottom out resistance” with a secondary air chamber and valve 1/2 lb lighter than coil conversions and only 20 grams heavier than same amount of tokens or spacers Maintains your fork’s air spring compatibility 36mm version fits 2018+ Fox 36 with NA2 air spring and Marzocchi Z1 Bomber Air forks. Not compatible with NA1 air spring or Z1 Coil forks. Not compatible with Fox 36 EBike forks 3rd party web sales (eBay, Amazon, etc.) are strictly prohibited by the manufacturer