Vacbed one way valve

Hello everyone,
I am a new member of this forum and a vacbed lover.

I am holding a silent air tight vacbed form slinkyskin (http://www.vacbed.co.uk/).
But when I switch off the vacuum cleaner, the vacbed doesn't suck very tight.

I got a spring check valve from slinkyskin      , but I think it's not very efficient, some air get into the vacbed after I turn off the vacuum cleaner.

Is anyone know about which type of one way valve is best for the air-tight?

I have seen about the video of vacbed from kinkengineering, which is really good at air-tight, Any anyone know what valve did they use?

Many thanks and sorry about my english mistakes.

Although an airtight valve is needed for your vac bed, I think I would have that leaks a little. And this is why.
If your vac bed is are tight, there is a very good chance you could get into trouble.
If the valve leaked a bit, like a tire with a slow leak, sooner or later you will be free.
But that's just my thoughts.

A one way valve can be made using a few pieces of plumbing fittings and a rubber ball, I suspect the valve in the image is similar to this style.
The ball is held against the seal by a soft spring, but the vacuum cleaner is strong enough to work the ball against the spring allowing the air to be pulled out. Then when turned off the spring pushes the ball back against the the valve seat, but the now low pressure in the vac bed also pulls the ball tight.
If the ball to valve seat fit is not good then it will leak.
But as @Tinker D said you need something to leak somewhere or you will be stuck.
Other people have a T piece in the pipes that has an ice bung in it, this will eventually melt and release you.

[Like Ra]

Found on eBay:
vacuum bed air valve 1
vacuum bed air valve 2