LD Mountain Centre says:
Like Nikwax Tech Wash, TX Direct Wash should be part of your household product armoury if you have a lot of outdoor gear to look after. Designed to work primarily with waterproof and breathable membrane fabrics TX Direct wash will also add water repellency to all waterproof face fabrics encouraging water to form beads and roll off the fabric rather than soaking in.
Nikwax TX Direct Wash-In Features
Nikwax TX Direct waterproofing for wet weather clothing, with wicking/absorbent liners. Adds water repellency and revives breathability. Recommended for Gore-Tex and other water proof fabrics. Use the Nikwax TX Direct regually to help improve the lifetime of your garments.