As usual, there are three different external key functions:
- The priority key function: can switch the cylinder between the service position (S) and the standard position (I) as well as unlock the cylinder in both positions.
- The standard key function: can unlock the cylinder in both positions, but is not able to change the access authorisation (S/I).
- The service key function: can only unlock the cylinder in the service position (S). As soon as the cylinder is set to the standard position (I), the service key cannot unlock the cylinder. On the inside, all three keys are always authorised to operate the cylinder, regardless of the defined position on the outside. You can order this option when ordering a thumb turn cylinder by selecting the 'TAF' option.