This has been useful for years in climbing, but is just one of the many forms of shackles. But eventually, I was lifting rather than I used to, and feeling much better than ever. "NO REST" really doesn't mean no rest. https://gitea.bestfulfill.com.cn/colettemerriam/5016955/wiki/Picking-The-Suitable-Kettlebell-Size%3A-Some-Tips