Adults 5'9 an down would be able to squeeze into these as alternative to expensive 2lbs sleeping bags with the only tradeoff being temperature rating an the bag maybe coming up to their shoulders. Otherwise great for kids. I do believe these to be zip together compatible if you try, (at least they look that way haven't tried).
The sleeping bag is made well, light weight and a nice color but I hate the way it feels. It is polyester and is like nails on a chalkboard to me. It also states 35 degree weather but I froze sleeping on my bedroom floor. I had to add a fleece blanket and fleece pjs to stay warm. I would return this in a second if I could.