I feel like these brushes are a little thin, (meaning ) there’s more metal than bristles I found whenever I was cleaning my glass piece I would scape bare metal against glass. & for $13 you can probably find something better.
Only brushes I’m ever going to use now. Easy to bend and use for your type of glass. I recommend after one use soaking your brush in smoke soap for 24 hours.
The only problem I had with mine was that it gummed up right away and even after I tried to clean it remained gummy. I don't think this really had anything to do with the brushes but the fact I hadn't cleaned my pipe in over two years so there was gunk on gunk on gunk. I even thought about naming my pipe Tony Gunk lol. I really loved the brushes.
I like them wish they had a bigger one..