I love coldbrew but the cost of a glass makes my grad student budget cry. I got this coffee sock last summer to start making my own.  I like the material of the coffeesock and the metal loop that can be placed over the end to keep the grounds in. It’s cotton so it can be washed and reused as many times as you like. It’s desirable because it’s extremely easy to use (grind coffee, put in sock, put sock in water, let sit) and very cost effective. It has become a niche kitchen staple for me- can’t wait to dig it out when the weather gets warmer.