MarinaBetta Ornament, Circus Rings, 12233

I have a .5 gallon tank for my betta fish, perry. i want to find him another toy/decor so he doesn't get bored. is this too big/is my tank too small?

Is the inside of the rings smooth and safe for bettas?

how tall is it ?

Is this item what’s pictured (a stack of swim thru hoops) or what’s described (a shell)?