Good quality, made by F.A. Italia
There are two different types of selector box for the motors of the PX range: “PX MK1” and “PX EFL/T5”, this is the early PC MK1 type.
 The way to check which one you have is to put a flat object (ruler) across the selector pawl in 3rd gear, this should be raised by about 2mm (see picture 3 + 4). On some of the versions can differ by up to 1.5mm as the manufacturers production tolerances can vary, and when built, the output shaft, selector rod and selector boxes were combined in different ways. This means it can jump out of gear,  but these FA selector boxes are very good and will cure this problem.....

This selector box is suitable for the following models:
P80X, P125X, P150X, P150S 1°, P200E and also used on early EFL/crossover PX's - PX80E, PX125E, PX200 E (Original part no: 138880)
 
Don't forget a selector box gasket! Available here: