The OEM design is held in place with a standard plastic locking clip. We also offer a special design with a thread on locking clip. Both of these adapters use an internal dual o-ring seal to ensure connections are leak free even under high pressures. We have used the 1/4" adapter on RSX and 8th Gen Civic fuel feed (firewall) hardlines and the 5/16" adapter fits all of the stock EFI K-Series fuel rails we have seen so far. If you want to measure and confirm what size EFI fitting you have, simply check the line thickness with a 1/4" or 5/16" wrench.
Generally Ships in 5-10 Business Days