TRRS reed block spacer, helps with smoother power off the bottom to midrange. 
 
Gasket required on the spacer to bike side (sold separately - 14007TR100
 
Fits:
TRS One 125/250/280/300 (All years)
TRS One-R 125/250/280/300 (All years)
TRS RR 125/250/280/300 (All years)
TRS Gold 125/250/280/300 (All years)