Metallics JBLW12 Washers 1/2 Split Lock Sbr (Jar 100)

The JBLW12 is a 1/2 inch split lock washer, so it seats under nuts and bolt heads on 1/2 inch diameter fasteners. Its inside diameter is sized to the 1/2 inch bolt, not to the wrench flat, so match it to the thread diameter rather than the hex size.

Silicon bronze is what the JBLW12 is made from, and that is the reason people specify it: it resists corrosion in wet and marine environments far better than plain steel, and it pairs naturally with silicon bronze bolts and nuts. Keep in mind it is a dissimilar metal against galvanized or stainless hardware, so for grounding and exterior runs it is best used with bronze or brass fasteners rather than mixed with zinc-plated steel.

They do different jobs. A split lock washer like the JBLW12 has a helical gap that digs into the nut and the mating surface to resist loosening under vibration. A flat washer only spreads load and protects the surface, and does nothing about back-off. On equipment, conduit supports, or anything that vibrates, the split lock is the one you want; on soft or slotted material where you need bearing area, stack a flat washer under the lock washer.

Each jar holds 100 of the 1/2 inch split lock washers, and the jar itself is the pack format Metallics ships them in. The full jar weighs 1.41 lbs, which is a quick way to sanity-check a partial count on the truck.

The jar measures 3 x 3 x 2.7 inches, so it drops into a standard small-parts bin or a service body drawer without decanting. That is the container, not the washer.

Metallics lists the JBLW12 for the electrical, plumbing, heating and air conditioning trades, which is where bronze hardware normally shows up: panel and enclosure mounting, strut and hanger assemblies, and grounding hardware. Nothing about a 1/2 inch split lock washer limits it to one trade, but it is stocked and sized for those installs.