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1-5/8 Inch Fill Cap
1-1/4-12 Straight Thread
Cap Weight: 1.06 oz.
Without Lanyard Boss
Includes O-Ring
(Cap Replacement O-Ring is C73-749)
2 Inch Fill Cap
1-1/2-12 Straight Thread
Cap Weight: 1.62 oz.
Without Lanyard Boss
Includes O-Ring
(Cap Replacement O-Ring is C73-769)
2-3/4 Inch Fill Cap
2-1/4-10 Straight Thread
Cap Weight: 3.32 oz.
With Lanyard Boss, Accepts Lanyard Chain Kit
Includes O-Ring
(Cap Replacement O-Ring is C73-788-A)
4-1/4 Inch Fill Cap
3-3/4-8 Straight Thread
Cap Weight: 7.86 oz.
With Lanyard Boss, Accepts Lanyard Chain Kit
Includes O-Ring
(Cap Replacement O-Ring is C74-788-A)
The lightweight, non-vented cap features positive grip finger notches that are easy to get a hold of. Prime 6061-T6 billet aluminum is precision CNC machined into a lightweight, attractively designed cap; featuring quick-start coarse threads. Each screw on Cap is fitted with a Buna O-ring; positive sealing and "radially squeezed" to hold the cap secure.
This design uses a radial squeeze action on a Buna O-ring for a secure seal. Precision machined quick-start coarse threads make using these caps a breeze.
The large selection of Pro-werks’ mounting bungs are crafted from Steel, Aluminum or Stainless Steel and available in both weld and bolt-on styles.
To compliment the color coordination of your project, the caps are finished off in Pro-Werks Brilliance anodized colors in your choice of Black, Red, Blue, or beautifully Micro-Polished aluminum – the finishes are impeccable!

Easy Turn Fill Caps come in many sizes and are packaged as complete assemblies with your choice of one of the many versatile mounting options, or each component is also available separately

Be sure to check out the entire line up - Billet aluminum Easy Turn Fill Caps are a Pro-werks specialty.
You can always count on Pro-Werks to do it right!

"I use your bolt on caps and bungs on my carbon fiber Cummins common rail valve covers. Love the quality. Thank you."
– Randy Davis, Owner of OldSkoolFab, Inc.
"I upgraded my fuel cell to an Easy Turn fill cap assembly. It wasn't long until all my friends did the same. Great product!"
– As shared with us at the PRI Show
Ships within 48 hours · Estimated delivery Jun 20 - Jun 25
US$40
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