Word of warning to any k6 users or people considering buying one, the bearing is not stainless and will rust over time, especially if you do RDT. I dropped mine in some vinegar for half a day and sprayed it with wd-40 on it and it's mostly fine now, not as smooth spinning as before but it doesn't squeak or offer much resistance anymore. Still something worth considering.
Another thing, if you loosen the silicon grip, just take it off. Trying to grinding with it slipping around is way harder than just not having it.