i keep most hatchlings in a 6 quart tub with 1 small RBI hide. the thing with the medium RBI hide is that they are too big for a 15quart tub which is my next size up for when a BP outgrows its hatchling tub. see:
the mediums are like more than twice the size of the smalls:
i guess u can turn the mediums sideways but there's now only room for a waterbowl.
at this size and age, i like to offer a temp gradient with a warm and cool hide. so i got these "small" hides from The Bean Farm. they're bigger than the smalls, smaller than the mediums.
i can fit 2 into a 15 quart tub.
(i forgot to take pix of two in the tub. :\ )