If you’re not familiar with homologation, it’s a process used by the CIK in Europe to register kart equipment. It’s a measure to try and confine the number of changes made to them and acts as a revenue source also.
I think (as NikG) that this is a VEN 04 system.
From various sources the VEN 04 rear pads are rectangular 64.7mm long.Fronts pretty much square 41.8mm long.
I think the rear pads in Jorge’s first pic.are VEN 08 pads which are shaped as shown but start off 78 mm long.ie. previous owner got wrong pads (VO8) and cut them down to fit.
Problem arises because the VEN number does not correspond to the homologation number. A VEN 08 Brake has homologation 16/FR/14. and I’m pretty sure the homologation for the VEN 04 system is 15/16/FR/08.
Altough the document above quotes VEN 06 ,on page 1 it refers to Model: BK-04-125.
So Jorge if you measure the rear ‘pads’ you took out at around 64.7 mm long, and the fronts at around 41.8 mm. long you should be safe to go for the VEN 04 gear imo.