An inimitable trainer, acting as a substitute for a boxing speed bag!
Pneumatic trainer - because there is air inside the ball, hence the name of the pneumatic boxing speed bag... I didn't invent the bicycle and learned about this device about 20 years ago when I was boxing, but there was a different elastic band - round and thick, which was replaced by one from underwear, a cap was not worn on the head, because it was in great deficit, but a sewn fabric band around the head with sewn-on crossed bands (as a neck muscle training device), and the elastic band to the ball was attached in the most cunning way, because they didn't know about the existence of adhesive tape yet
