Umm, I’m no expert – we bought ours at Lovehoney, I can’t find the exact one but if you search restraints there are loads of options. It connects up under the bed. But we tend to have it come over the top and bottom more than making it into a big X shape, which is more comfy. It’s padded velcro straps though, never had a problem with comfort.
It’s a huge turn on for him though, being restrained while I play. Because he’s quite dominant it’s the one thing that truly reverses the power in our play time. We maybe use them a few times a month, and always for things like post orgasm torture.