Fox 802-03-015-KIT Black Anodized Billet Aluminum Schrader Air Valve Cap For 803-00-977 End Caps

The 803-00-977 reservoir end cap upgrade for stepped 2-1/2" aluminum reservoirs, that Fox manufactures, includes economy plastic Schrader valve caps. Fox later came out with the o-ring sealed 802-03-015-KIT caps. The 802-03-015-KIT cap includes a 029-03-013 o-ring. These caps keep debris and moisture out of your reservoir and the o-ring also prevents the cap from unthreading from vibration while you drive.

You'll usually see the stepped reservoir sleeves and the low profile reservoir end caps on Fox UTV shocks and also some aftermarket Fox truck shocks. See below picture for reference.