In uk.d-i-y, PJ wrote:

At my local Maplins they have Satellite TV Cable FT100 in 100m roll at 24.99
pounds sterling. Is this the same as CT100?

Probably a cheaper near-equivalent, but maybe the honest stuff. It sells
at 25-30 quid the 100yd reel at not-taking-the-Micheal-on-price places.

Also, they have Satellite Cable FT125 in 100m roll at 59.99 pounds sterling.
Any idea what that is?

CT125 is the next size up from CT100 - slightly bigger outer diameter,
slightly lower attenuation losses over distance, more often used for
distribution feeds in bigger installations (e.g. for piping sat TV signals
or cable-TV feeds round a block of flats); there's CT167 and CT233 sizes
which continue the trend upwards in diameter and lower losses. All of these
more exotic sizes share the same design impedance as CT100 - 75 ohm; but
because they're sold in much lower quantity than CT100, you pay a b-i-g
price hike for them over the CT100 (a bit like the hike in 4mmsq mains
cable compared to 2.5mmsq!). For a domestic installation with "normal"
lengths of cabling, you don't need anything beyond CT100, and it gets
harder - indeed impossible! - to get coax plugs and sockets to mount
neatly to the larger sizes.

HTH, Stefek