The mattress covers the gap between the twin beds. There is an adjustable strap to keep the mattresses pulled together. I even have to sleep with the head of my side of the bed up on a incline and it still holds everything in place without sliding.

Works as advertised. We have had bed bridges previously that were useless. Only issue is it does not provide directions on how to install the strap.

The horizontal bed is perfect for rooms with limited wall to ceiling space. The result is a nice bed, with durable hardware. Easy to follow instructions.

The horizontal position is not so easy to work with, wish we had gone with the vertical. They only give you measurements for where to place their fittings on the wood. They just tell you it's in their assembly instructions.