Sent an email to GO asking them and they came back with the following info:
"Most likely you use our standard sized folding buckle. The segment length of this buckle is 39.0 mm and altogether it is 44.0 mm long. Fortunately, we also have a short version which we recommend for slim wrists with a segment length of 33.6 mm and a total length of 38.0 mm. Here you can see the total length and appearance of the two different buckles:"
