6-8 speed chains are a little wider than the chains for a 9-speed or 10-speed each is which are different, narrower, and which have a shorter life than a 6-8 speed chain.

If you have a 10-speed, use a 10-speed chain. If you have a 9-speed, use a 9-speed chain. If you have a 6-8 speed you can use any 6-8 speed chain.

If you try using a narrower 9-speed or 10-speed chain on a 6-8 speed crankset, I've been told that you may have a problem with the chain falling between the front chain rings because the chainrings could be spaced wider than the width of the chain.

I've switched to KMC chains recently and bought a Park Tool master link tool to make it easier to open and close the KMC "Missing Link" master links. A single Park Tool master link tool will open and close links. There are two separate KMC tools for opening and closing links.