i believe the jagwire housing is intended for use as brake or der. if i remember correctly the jagwire website listed a single ripcord housing without designation of application (brake or der). they also list sets with the corresponding cable.

i have some jagwire ripcord i got from nashbar which is sold as a brake housing and cable set (the housing is imprinted jagwire ripcord). i have actually cut it open and examined it.

it has lengthwise compressionless-type steel wires (like der housing). this layer is covered by some plastic, then an outer layer of woven kevlar fibers. the kevlar supposedly gives it the burst strength needed for brake applications. so this stuff can go either way. it is stiffer than conventional brake housing with the spiral wound steel. the jagwire bends pretty much like compressionless housing.

nashbar doesnt seem to have a der. version of this housing.

the nashbar branded housing is much cheaper than the jagwire ripcord, $4 vs ~$20.

btw. i recently purchased several 'der cable and housing" sets from nashbar. its made by delta (they used to have the ads side by side for easy comparison) but cheaper, ~2 bucks. turns out i got der cables with spiral wound housing, not compressionless housing. what a deal huh.