Both of mine also wear break away collars, and I have them so loose I can fit four fingers underneath the collars, even though the requirement is only two. They are both indoors, but I also worry about a door dash. Another reason is if I have to get up in the night and it's dark, I can hear their bells and I won't trip over them!!! Tilly also loves to sneak up behind me and roar down the stairs between my legs, but I can hear that little ding-a-ling (and yes, I do mean that in more than one way!!) and I can freeze until she has zoomed through! I would recommend it, especially if it's loose enough. As a testimony for the break away collars, I was coming out of my house the other day and found a cat break away collar laying in the walkway (I live in a townhouse). I think the cat jumped over the gate and the collar got stuck, and it just came off. I was able to return it to the owner because Cosmo's address was on it