A few tips about these moss hides:
they sometimes will poop in them so watch for that. Just remove the pooped part and clean that area; you don't have to throw out the whole thing. Every few month replace the whole contents with fresh in clean container.
They will flatten the moss down or drag some out so you will need to occasionally replenish the packing.
Replenish the moisture occasionally; pack it in firmly then squeeze out the excess water.
They like tight spaces to squeeze into so you can stuff the moss in the container generously.
I use the soft orchid moss from Lowes or any garden center that sells orchid supplies.
Baby bulls enjoying their moss hide.