They usually stay near. But you never know. Predator can come and take them. Can get scared and run off. The best choice is to keep them in some kind of playpen. Or using a harness. If you would like to have them free on the ground but still safe. I actually make rat harness that I sell. Verry popular. Something I came up with my self, using the old show harness. Also called 8-harness(here in Sweden). The name probably came from its shape, like the number eight.
Started with plans on making harness around midsummer 2009 when I was taking two girls from my litter with me on vacation. Was supposed to give them over to the new owner. But they could not pick up the date we had agreed. So standing there with no more cage then the transport. I made two small harnesses for them. So they could run more free as mutch at possible. I let them be free in my bed when sleeping. Gave long leash that I put on my toe. In case they would get down on the floor, so I could find them again in they got under any furniture. But they slept by my side for two days in a cabin. Made my first real one after several hours trying out materials and different parts. Trying to figure out the safest harness that was easy to move in but also looking good. And one that didn't weight too much on them. So the 1 July 2009 i made my first rat harness. Sold it ever since to people who want one. The same model as I made up back then in 2009. I have only added a part in the back to keep away pressure from the neck and make it a bit safer. The blue harness is my first. The purple is with the new upgrade.