Features and Benefits: Sizes clearly labeled for easy identification and accessibility; Plastic rail is more durable and lighter than metal; Holders adjustable for individual preference; Recessed springs hold sockets; 1/2" drive size (metric), 8-24mm socket size, 17 holders; Nylon rails are pre-printed with socket sizes for easy identification. 1/2" drive size (metric), 8-24mm socket size, 17 holders. Features recessed springs to hold the socket. Rails include mounting holes.