INSERTA^® ILR Lockstack D03 Retaining System includes stacking fasteners that eliminate the need to size and cut thread stock for D03 sandwich stack assemblies. The system also includes a novel isolation retainer that engages the fastener heads to resist loosening during disassembly of the directional control valve or other stack component(s) above. Use the Lockstack system to reduce labor costs and sandwich assembly headaches, while adding value and integrity to your sandwich assembly.