Flack jackets are sort of dark metallic green/grey. The red bit is to cover the exposed cable between the cable mounts on your top tube along with some special black ferrules that make a 'seal' between the outer cable and the red bit.
If you run full length outers, you won't need the red bit. However, some of these cheap mail order packs don't have enough outer to do it. They're OEM sets used to equip a shop bike with short runs. They have less (none) spare ferrules, etc. ALLEDGEDLY!
I bought a set for 10 quid from the WOllyHatShop, they came with long enough runs for a full length outer to the rear.
I didn't need it though as the Klein has internal cable routing. I swapped out the internal guide for the red housing and the sealing ferules fit inside the frame and into the red tube. THey've been fine so far and seem much smoother than cheap rubbish that I've used. Not sure if they're worth the 20/25 quid that they should be mind!
Haven't used the others, but have used gore now for about 7 years, very happy with them, good life from each set, generally end up changing when shifters bust rather than through cable wear.
Flak Jackets are very dark green and red (unless you're a lucky b@stard and can run the outer from mech to shifter). In my experience, they are maintenance free. Highly recommended.
Have just fitted the Avids to a friends bike and run the Gore ones on mine. The Avids are have really tasty carbon fibre outers but the red coloured tube interconnections look a bit Naff. The whole system looks good(after warming the interconnection tubes with a hairdryer to straighten it), fitted well & was easier to fit than the Gore ones. A decent addition to make the whole system sealed would be something to put over the exposed bit of cable at the rear mech (As on the Gore). The Gore system has crap instructions but is (by design) better sealed. I can't remember if the outer was a complete long length on either. Performance shiftwise both are really good with light action and positive shifts. My mate even had problems with overshifting as he didn't realise how bad the old cables had become. Only time will tell but I suspect the Gores will last better. £20 's a lot for cables but decent shifting I.M.O.H is a must. All the best T.
Flak Jackets are excellent and well worth the money. Neil is right about the outer though so make sure you cut to the right length. The carbon fibre weave looks great though.
