Tweeti have to use a 140# bag. it must be hung from the ceiling as the pedestal bags suck. heavier bags allow you to focus on power without having the bag get pushed away and hyperextending your elbows like on the light 50-70# bags. i also like banana bags as they bow in the middle and dont swing wildly like a boxing bag.
we have 4 different bags at our little camp for different purposes. the 140 banana gets used the most for Muay Thai.