There’s a catch… actually there are two.
The first is that they are rather expensive. You need the PCB mount plugs (available as straight or right-angle), then you need the housings for the cables and for the housing you need the small metal sockets. Molex as a brand are rather expensive and many suppliers; like Rapid Electronics in the UK have alternate sources that seem just as good but are MUCH cheaper.
The second catch is a real pain in the backside and something that I’ve just fallen foul of.
A cable I assembled had two connectors on it; one at each end. The cable connects a simple LCD display module to a project PCB. However, once everything was working I decided to change to an LCD that has a built-in backlight. Character LCDs typically have a 16 way connector which is great as that’s the largest size available in the Molex range. However, some LCDs have some strange pin numberings with pins 15 & 16 (typically used for the back light) appearing either before pin 1, or after pin 14 on the display. Needless to say, my two displays were one of each.
Using a very small jewellers screwdriver, it’s possible to “pop” each socket out of the housing and reposition them. Unfortunately, and here’s the catch, you stand a very good chance of squashing the socket so that when it’s put back into the housing and even though it clicks home, it won’t make contact with the metal pin on the plug.
I’ve just spent several hours wondering why a working project has just suddenly stopped and it was because one of the sockets I re-positioned was slightly squashed and wasn’t making proper contact with the pin on the plug.
If you do remove the sockets, ALWAYS check the cable works afterwards.