The '123UNI' is designed to work on '2CV' 9 hp, 375cc, A53, M4, A79/0, M28, A79/1 and M28/1 engines in conjunction with the stock black coil. (6 Volt type for 6 Volt battery, and 12 Volt type for 12 Volt battery) The dwell is automatically adjusted.

Upon installation, the user has to check his engine plate ( "A", "AZ", "AM", "AYA", "AM2", "AYA2", "AK2", "A06/635", "A06/642", "AM2A" or "A06/664" ) and look in the manual which setting of the rotary-switch is appropriate.

There also is a special setting for M28/1-engines running on LPG or on Ethanol, like 'E85' as used in Sweden. ( 'E85' contains 85 percent ethanol, and 15 percent standard fuel )