Johnson Marines' locking nuts and locking rings come in a variety of thread sizes, thread counts, and rotations. They are used for different purposes and work with different Johnson model numbers and series.
This is a replacement for a Knurled Nut for a gate/pelican hook with a 1/4 in. (6mm) thread, 28 thread count, and a left hand rotation. It is compatible with items JH23/24301 and 26/27404.