All interlocking start with the correct key style selection. 

The main criteria for selecting your keys are the following : 

1- how harsh is the environment ? Select S, F, P for standard duties and choose instead the K and H for hard duties. In case of strong dust, select only KS and CS keys, since they integrate a dust production to prevent dust enter the cylinder also when key is trapped. 

2- Do you need many different key codes ? Are you worry for keys being copied at supermarket ? Just select A, P, F, K or KS style for maximum key differ availability and most difficult repeatability of keys

3- If size is an issue, but the environment is harsh, your best option is key style A.

IMPORTANT: safety of interlocking is ensured if no spare keys are available at any plant. Remember : interlock means that key is always trapped somewhere, so it’s almost impossible to lose it. We strongly recomment to avoid spare keys or master keys at your plant. 

In any urgency, KLS can provide repeated keys, just be receiving the key code you need.