this is to replace the spacers in the forks if you have any to make them more progressive and is adjustable so no need to add or remove spacers in the fork.
it is expensive compared to spacers but less hassle if you need to add and remove them.
http://singletrackworld.com/2016/12/mrp-offers-ramp-control-to-suit-fox-34-forks/
http://www.chainreactioncycles.com/mrp-ramp-control-cartridge/rp-prod157230?gs=1&utm_source=google&utm_term=&utm_campaign=Chain+Reaction-UK-PLA-PLA-All-DT-SE-Shopping+QLB+Manufacturer+Desktop&utm_medium=base&utm_content=mkwid|sdC6HE7Kp_dc|pcrid|161845658788|pkw||pmt||prd|574994UK
it is expensive compared to spacers but less hassle if you need to add and remove them.
http://singletrackworld.com/2016/12/mrp-offers-ramp-control-to-suit-fox-34-forks/
http://www.chainreactioncycles.com/mrp-ramp-control-cartridge/rp-prod157230?gs=1&utm_source=google&utm_term=&utm_campaign=Chain+Reaction-UK-PLA-PLA-All-DT-SE-Shopping+QLB+Manufacturer+Desktop&utm_medium=base&utm_content=mkwid|sdC6HE7Kp_dc|pcrid|161845658788|pkw||pmt||prd|574994UK
