Preferably of the type shown in Hippy's pic on the left and used with inner tubes with removable valve cores. Remove valve core from inner tube, insert extender, reinstall valve core into extender. Far better than the alternatives such as that shown on the right, IMHO.
Preferably of the type shown in Hippy's pic on the left and used with inner tubes with removable valve cores. Remove valve core from inner tube, insert extender, reinstall valve core into extender. Far better than the alternatives such as that shown on the right, IMHO.