DeWalt / Bostitch 9R188835 Seal For DWFP72155 DWFP72155R BTFP72155 BTFP72156 DA1564K N62FNB Nailer

9R188835 is a genuine replacement Check Seal used in pneumatic finish nailers. 
It is a critical internal component that ensures an airtight seal within the tool's cylinder and valve assembly. 
Functions : 
Pressure Management: It prevents air leaks, allowing the tool to maintain the pressure required to drive fasteners consistently.
Valve Regulation: It assists in the proper cycling of the head valve, ensuring that air flows correctly during the firing and reset stages.
Operational Reliability: Replacing a worn check seal is a standard fix for a nailer that is "hissing" (leaking air) or failing to fire with full power.