I bought the split King size and it did have a strap to hold them together but I still used a heavy duty zip tie as well. The only complaint I have is that the mattress slides a bit towards the outside of the bed when you adjust them so we are constantly pushing the mattresses together. I would still buy this again. The end bar holds the mattress in place so its not sliding down. Unlike my last adjustable base, the end bar on this bed is screwed in and cant come out.