Fitbit Zip box for dog collar (another one)

Box for fitbit zip to mount on a dog collar.

The slot for the collar is 27x3mm. The collars my dogs have are approx 25x2.5mm. The fitbit zip fits in VERY tight - not that it feels like it is breaking or anything, but I will not fall out by accident, even if you take the box of the collar.

Since the fitbit zip is shaped slightly like an isosceles trapezium, the fitbit zip will only fit into the hole in one way. There is nothing on the box to tell you how that is, but it should be kind of ob