Means are described for positively engaging a key in a keyway in a pipette and its support, to insure that proper dispensing position is maintained and that the pipette stays in the support. Preferably spring means are provided on the key for pressing against the keyway....http://www.google.fr/patents/US4931257?utm_source=gb-gplus-shareBrevet US4931257 - Positively engaged pipette and pipette support
