Longacre No. 50100 TIRELIEF Kit. Kit is all there and includes 4 more Tireliefs ($55 value) for a total of 10 Tireliefs.
TIRELIEFS™ Tire Pressure Relief Valves
Relieves tire pressure buildup as you race - automatically.
Use with quick change adapters or mount directly in your wheels by drilling a 1/8" NPT thread hole.
3-40 psi range
100 mesh inlet filter - to keep dirt inside tire from plugging TIRELIEF™
Lightweight aluminum - only 9 grams - won't affect wheel balance
Pro-Team TIRELIEF™ Kit
Preset your TIRELIEFS™ BEFORE you install them in the wheels. The setting tool uses your compressed air supply to accurately simulate tire pressure to set valves precisely.