i really don't know how to choose a right speed bag for home gym.What things really count on this?thickness - diameter - swivel adjustability - size of speed bag - (and most of all price)
after searching i conclude on this model:

Top Contender Adjustable Speed Bag Platform Style: MRSAP 2 Durable steel frame and wood platform measuring 1" x 30". Platform adjusts a full 24.5" and includes an E-Z Lock Pro Swivel (#PS-2)

...

Stub