Yamaha aerox 155 Yss G-racing Shock absorber 

HIGH-LOW SPEED

Adjustable Hi-Low Speed Compression a zenith of the compression control technology. H-L valve is designed to maintain and control the flow and the high speed valve is set to active when the oil pressure is too high so the shocks will not get Hydraulic Lock.

THREAD SPRING PRELOAD

Thread Spring Preload or adjustable spring screw. By threading the cylindrical shock absorbers, user can turn the preload to fine tune the spring and tighten a provided bolt to fix the ring in its position

REBOUND ADJUSTABLE

Rebound Adjustable is to control the recovery of the shock absorber. Fast or slow depending on driver needs. It is designed to have a volume control knob needle shaft Free Bleed oil through hole and the knob Rebound is designed to sense the adjusted time adjustment dial.