They're reuseable and allow the bottle to stand upside down, therefore collecting all the sediment. You can then remove the trap, leave the cap in the bottle and store your home brewed beer on its side in the fridge or drink it straight from the bottle.
I can tell you more about these but there is an excellent instructional video by an independent home brewer in the US available here which explains things much better.
I could do with trying some of these but the company who makes them is still looking for a UK distributor. So I thought, how about a bit of blog/twitter market research. Home brewers, can you tell me if you think they are a viable option.
Would you buy these so you could either drink homebrew from the bottle or lay it down in the fridge?
Do you prefer sediment in the bottle?
Bearing in mind they are reuseable, spares are available and obviate the need to use crown caps, would you pay,
a: £1 each for these
b: £2 each for these
Or do you think the price differential from using conventional crown caps outweighs the benefits?
Leave a message below. I'm interested to hear what the UK home brewing community has to say.