Climbing equipment- chalk bags
Chalk bags are usually simple, cylindrical-shaped holders for loose chalk. Firm, round openings for easy access are standard, perhaps with a fleece lining to better hold the chalk. The outer can be made from a variety of fabrics from cloth to leather or nylon, and most have a small brush holder.
You want a lightweight, small bag that you can get your fingers into quickly. Definitely get one with a brush holder, so when you're getting all that chalk on the holds you can quickly clean off the excess on the way down.
In this situation you'll want to get your whole hand covered in chalk up to your elbows, so a big bag is good...
Use your sport bag if you're wearing them on longer problems, but there are some extra large bags specifically for bouldering. (Leave them on the ground!) These have large capacity for holding lots of chalk for long sessions. They're great for a gaggle of rock monkeys to dip into. Most have a brush holder, essential kit for the well-psyched boulderer.
Large, deep, cylindrical bags are best for most trad situations, especially if you're on a long, multi-pitch route or on wider cracks. Often you'll want to get your whole hand covered in chalk up to your elbows, so a big bag is good. A medium-sized bag is nice for finger cracks, and those moments when you want to chalk-up your fingers quickly without getting lost in the dip.
Deep water soloing (DWS)
You'll need as many chalk bags as you can get hold of for ths! Do make sure that the fabric to be fast-drying: nylon and polyester are the best. Most DWS climbs are not too long so you don't need to carry too much chalk. Small and medium bags are best.