What kind of Steel Door Contact should I use?

Steel doors or windows can cause certain magnetic door/window contacts to malfunction.

Steel has a tendency to dampen the strength of magnets, and even render low-power magnets ineffective. This causes a major problem for sensors that monitor magnet gaps to tell if an access point is open or closed. To solve this problem, a user can employ the help of a strong magnetic sensor, like the 947-75T. Or you can simply swap out the magnets from the malfunctioning sensor with a stronger magnet from the MPS70WGB or the 947-75T.

As a side note, if you are having problems with the 5800MICRA, then you're not alone. This device, in particular, does not perform well around steel doors. Consider using the 5818MNL in its place.