I've seen these before but have not use them.
They *seem* to be an improvement over the serrated Schnorr washers, which of themselves are an improvment over normal , serrated-edge Belleville washers ( by having the "tip" of the serration offset to one side, to better resist the "unwind" motion).
They may have been discussed on this forum, especially with regard to CV joints.
- Wil
EDIT: Yeah, here--->
Questions on CV boots replacement.