ISO International Standard

ISO 3764:2016 specifies the types and fitting dimensions of mechanical and electromechanical watch-movements.

This International Standard is applicable to the five following types of movements:

– Type 1: round;

– Type 2: shaped round;

– Type 3: round with double cutting;

– Type 4: 5 ½′′′;

– Type 5: 6 × 8′′′.