I think the specifications on the startech website give you some precision on the maximum weight supported I personally just have 40 lbs max in this model
Yes, according to https://www.startech.com/Server-Management/Racks/3U-19in-Steel-Vertical-Wall-Mount-Equipment-Rack-Bracket~RK319WALLV#tchspcs , the weight capacity is 125.3 lb 56.7 kg.