The bristles are a plastic-y material that kief doesn't really stick to very well, and with only one row of bristles they don't have the depth for kief to get lost inside the brush. Perfect for unclogging your screens or scrounging up your tree dust into one central pile cause you haven't re-upped yet and you're just kinda fiending real bad oh god
So I haven't seen this one anywhere. But if you're smoking from a pipe (I don't use this with bubblers) go ahead and try taking your thumb off the carb and putting it back. Just tap the carb with your thumb a few times. It increases the air flow and you can get a bigger hit. The weed burns a little faster, which is either a good thing (trying to get a bigger hit) or a bad thing (trying to conserve the bud for your buddies). Anyway, try it out, it works.
When deciding between a few of course. small is great too :)
If I know I'm gonna store weed in my bad I will always put some lavender in the bag. It 100% masks the smell.