Chamfered OD for easy installation (injector end) Flared ID matched to plunger shape for smooth insertion (injector end) Tapered ID for increased pressure and leak resistance (glass end) Perfectly matched for all Delta Kits metal injectors Industry leading chemical resistant compound will not shrink or swell Using superior materials and proprietary design, Delta Kits end seals outperform the competition hands down. Don't be fooled by imitations, for fit, form, and function, nothing else compares.