My Bulgarian bag was a home made POS made from a car tire inner tube filled with sand, it weighed just under 28 kg. It lasted about 3 years before it split and sprayed my living room with sand.
It was the perfect compliment to my kettlebell training as it added a rotational aspect to my training that's hard to hit with Kettlebells.
They're one of the best functional training tools ever, especially for anyone doing BJJ or Judo or anyone wanting to get in shape.
HIIT sessions with one of these will get you where you want to be in very short time!