Two Size Markings – The size is marked in two ways, both as a high-visibility laser marking and a permanent stamped marking, Full-Length Socket Well – The interior well extends fully into the socket, which allows for better fastener engagement in more situations, Works With Friction Ring or Detent Pin Anvils – Smooth walls inside the drive end and a detent pin hole make the sockets compatible with both drive tool anvil types, Prevents Fastener Round-Off – Radiused corners prevent fastener round-off by applying force to a fastener's flat sides, rather than its corners, Socket Organization Rails and Tray – The twist-to lock clips on the rails hold sockets securely and can be repositioned anywhere along the rail.