Locking universal adapters hit tight spots The Mac Tools 1/2" to 3/8" and 3/8" to 1/2" Locking Universal Adapters, No. VX3UL/XV3UL, are designed to reach difficult angles and hard-to-reach fasteners. A locking collar holds sockets firmly in place and allows for quick release when finished with a job. The universal design allows entrance into tight areas with 360 degrees of swivel action for optimal access. In addition, the adapters feature a high polish, chrome plated finish for long lasting corrosion protection.