Concealed runners for frame and panel cabinets. 75# dynamic load capacity test to 100,000 cycles. 100# static load capacity. Exceeds ANSI/BHMA 156.9 requirement for Grade 1. LIFETIME GUARANTEE. EXTREMELY smooth running on nylon rollers. Self-closing BLUMATIC action. Locking devices keep drawer fastened to the runners yet permit easy drawer removal. Use with drawers up to 5/8" thick. Designed for overlay and inset applications. Locking devices are required, purchase item BT51.1700