Universal Replacement Bar End Adapter for Armor Handguards by ZETA®. Bar Inner Diamater: 13.5mm-19.0mm. This top-grade product is expertly made in compliance with stringent industry standards to offer a fusion of a well-balanced design and high level of craftsmanship. Manufactured from industry-leading materials using up-to-date equipment, it ensures everlasting reliability and enduring value. This product is distinguished by total quality assurance, unsurpassed by anybody else.