22551972 inlet valve rebuild kit contains all parts needed to rebuild the inlet valve and many Ingersoll Rand UP6 and UP6-50 rotary screw air compressors. It is recommended to use this kit every 8,000 hours or 2 years. If your compressor is slow to build air or it leaks from the inlet valve, this kit may solve the issue. Often times this is refereed to as an Unloader Repair Kit.
22551972 is an OEM part manufactured by Ingersoll Rand.