Metallics JLWC172 Washer 1/4 Split Lockwshr Cu (Jar 100)

The JLWC172 is a 1/4 inch split lock washer, so it seats under a nut or bolt head on 1/4-20 or 1/4-28 hardware. It is sold as copper split lockwasher.

100 pieces per jar. The jar pack is the unit, so one order gets you a wide-mouth container of 100 of the 1/4 inch copper split lockwashers, which is a practical count for a van or a panel-shop bench rather than a bulk box you have to decant.

That is what it is for. A split lockwasher's offset ends bite into the nut face and the mounting surface as it is torqued flat, keeping tension on the joint when equipment vibrates. In copper, like the JLWC172, you get that holding action without introducing a steel-to-copper interface at the bonding point.

No, and they do different jobs. A flat washer spreads load over the surface and protects soft material; the JLWC172 split lockwasher is a spring washer that holds torque on the fastener. On a bonding screw that has to survive vibration, the split washer is the one you want, and plenty of installers run both, flat against the surface with the split washer under the nut.

Copper handles outdoor and damp exposure without the plating failures you see on zinc-coated steel, which is why copper hardware is standard on exterior ground rod clamps, water pipe bonds and service grounding. The JLWC172 is solid copper rather than plated, so there is no coating to wear through at the washer's bite points.