Stanley Proto JKE16 Check Nut Wrench 1/2",Stanley Proto,JKE16" /> Non-reflective black oxide finish for use where non-plated products are required. Ultra thin profile improves access in close quarters. In confined spaces, the 15 head allows for a full 30 rotation by flipping wrench over. Use check nut wrenches to tighten jam nuts, check nuts or lock nuts.