This gym is giving $10 off if you guess what thisequipment is. It looks like a bag. (Link is clean, just regular photograph).
Help me save $10 . . .
Probably sand bags.
Yep, sand bags. Actually I think those might be water bags. Same use as sand bags but adds a degree of difficulty because the water moves more.
They’re not producing the same shape that bags full of water would.
I think that they’re gym bags: My intelligent deduction has to be worth 10 bucks!
It’s a mimic octopus. Everything is a mimic octopus.
???
: pokes apple very, very cautiously :
My first guess was that it’s some sort of Bulgarian bag, but the shape doesn’t look right.
That big white circle? That’s a hula-hoop, surely?
I’ve used those at the bootcamp class I used to go to. He had sandbags, and he had those which were water filled. Apx 35lbs up to 75 lbs or so.
So No Wikipedia Cites, did you get your $10 off?
And, more importantly, am I right? 
Stingray ?
That’s what you use for the midget toss when you’re fresh out of midgets.
Lucky you… The guessing is the easy part! As long as they don’t care if you’re right…