Top tier FPV backpacks are made by Torvol, iFlight,.. but you can find cheaper ones which will be quite similar to the top tier products.. a very good source in europe is Drone-FPV-Racer as well as Rotorama
HGLRC B1 is super solid. Held up pretty well through torrential downpour in Chicago a couple weekends ago too (although I would still recommend using a fully waterproof cover)