the 38, 39, 42 sizes will certainly be double-specific unless otherwise stated. The outer chainring sizes (50, 52 of which only the 52 is on sale) will probably work OK but
a) on any chainset the pins and ramps come in matched sets these days; manufacturers sometimes make different 50T chainrings (say) depending on what size chainring they are intended to be paired with. Thus shifting performance is unlikely to be quite as slick as with an OEM chainring if a mixed set is used. Aftermarket chainrings often don't come in matched sets so the shift quality isn't quite as good in any case.
b) the offset requirements for 9s and 10s chainrings can vary slightly depending on the chainset; it isn't absolutely guaranteed that an aftermarket chainring will work perfectly for this reason; some require shims to be added and others won't work at all.
c) the stronglight chainring depicted is for a standard spider, not one with 'a hidden fifth bolt' behind the crankarm.
I'd probably take a punt on it but I note that the ribble website says 'only one in stock' or something, so I wouldn't hold my breath....
cheers
