From what ages kids is this good ?

Yes there are double tubes and there are single tubes depending on the conditions we allow multiple single tubes to be attach to each other. double tubes cannot be attached to anything the child must ride in the tube not on the parent's lap

I would say the same 2 and up

I'd agree with @mirocic 2 and up seem like good age limits.

So you have double tubes @mirocici

I was with 7 and 10. Both smaller than average, rode solo and had a great time.