I was looking for a tube for a neighbour and found these
Info from Evanscycle website ..
German technology since 1871. Over 100 years of experience in the manufacturing of bicycle tyres has made Continental into a unique, outstanding company. This uniqueness shows in the range of Continental products for bike riders. The Continental 26 x 1.75/2.5 Schrader valve MTB tube is a top quality replacement inner tube.
These are far better than unbranded cheap tubes.