I save these devices from lactostasis, quite effectively. I can not name them indispensable, but when lactostasis still befall, I was glad that the pre-bought a ready-to-use packs, and I did not have to invent anything. The temperature is kept very well and bring significant relief in the event of problems with feeding. Of course, they must be used in conjunction with other activities (massage, limit drinking, frequent attachment and so forth.)