Pitstop Road Racing Kit 75ml (1 Pcs + 1 Strap)

only works 50% of the time, nice to have on short halls for slow punctures, but does not replace anything in your repair kit, you still need it all. So a bit expensive and bulky for what it is.

I carry one of these during races. It is for emergencies only to save me from having to change a tube during a race. The hole has to be relatively small so I wouldn't bother trying it on mtb tyres