LKS-440-2 | صواميل ذاتية القفل من PEM #4-40 | فولاذ (50/عبوة)

Used a few of these on a tight bracket assembly and they locked up perfectly on the #4-40 studs. The steel feels robust and the self-locking feature held fast even after some vibration during testing.

Steel's definitely the right choice here—the threads held up perfectly when I cinched them down on a #4-40 stud, and the locking action kept things snug without needing a ton of torque. The 50-count pack is a solid deal for the price, too.

The little nylon insert grabs the threads right away, so I don't have to worry about these backing out on a vibrating assembly. The steel body feels solid, and the 50-pack is plenty for the small batch of #4-40 fasteners I needed to secure.