This twist linkages are made from high quality material and they are equipped to guarantee a perfect tuning.

Type 1 means Type 1 engines with twin carburettors (IDF/DRLA/KADRON/ICT). These are not appropriate for engines with Porsche style cooling.
Type 4 means Type 4 engines with twin carburettors (IDF/DRLA/ KADRON/ICT). These commands are also used on every Type 1 or Type 4 engine with Porsche cooling.