The Racing MCA-18K automatic cut and re-insert device is available for most leading makes of ovedrlock

The Racing MCS6 metering unit
Up to 6 different tension values
Will fit almost any make or model
Change tension by knee press or stitch count
Pre-tension facility
A cost effective way to meter accurately

8 pre-programmed zig zag patterns
Facility for one custom pattern
Models available :-
Brother B855E standard machine or
Brother B856E under bed trimmer
Racing MC S6Z-57 metering unit with 6 tensions
Racing MC 18Z-57 metering unit with 27 programs.
Racing MCA 18Z-19 metering unit with 27 programs with auto cut and re-insert