http://www.nord-lock.com
Here is a video that they posted comparing multiple methods of keeping hardware from working loose
https://www.youtube.com/watch?v=IKwWu2w1gGk
Here is what the Nord-Locks look like
![Image](https://s19.postimg.org/t8vmjk5gz/IMG_20170923_193641891.jpg)
I got the ones that I am using from McMaster
https://www.mcmaster.com/#91074A115
I have been adding these to several bows over the last year or so and have not had one come loose on its own. Bows I have added them to so far are M405, Exomag, Phoenix, and a Micro 355. The split lock washers do very little once they get compressed.