One.

One

one of these will join your chain.

Only one as they come as a pair.

You just need to buy one link to join a chain (the two halves of the link are supplied together).

Only one "link" required. I carry one in case a chain breaks.

Purchase just the One (1) unit/item. The link is in two parts, just break the chain and remove the next pin as well which will leave the gap to engage the connex link.

Just the one.

You need just one. It comes as a split link, so you put the two halves together and join the chain

They come as a pair i.e. a link to join the chain.

Yes

Definately works with SRAM, I have used it on one. Can't see why it wouldn't work for shimano too.

I use it on my Shimano 9 speed with no difficulty

I have fitted these chain links on both of my bikes and have had no problems.

Yes, I have used with both - and seen them used with a KMC.

Yes, it is very easy to release and it can be reused. Mine lasted three chains (but do bring a spare if it is getting old).

Yes it is really easy to release without tools and it can be re-used indefinitely

Yes it is quick release. You just have to sqeeze the links together and they will pull apart.

Of all the links I have used, this is the easiest to unlink/re-link. No tools required. Much better than SRAM/KMC (and the cheaper Wippermann quick link that comes with the cheap 8sp chain). I have used some of mine on 3 or more chains/at least 4,000 miles.

Yes
Yes