The 'Glass Tube Key' is a tiny glass tube used as an alternative key ('user key') for the m-Lock RFID ignition lock.  
Please note the possible significantly reduced operating range in comparison with the Teardrop Keys (5-10 mm). Furthermore, the operating range is subject to wider tolerances.
A maximum of 3 keys may be associated to one m-Lock at the same time. For teaching additional keys the associated 'master-key' to the m-Lock is required.