Note for watercooling beginners:
The connections for hoses (7 / 16 ", 3 / 8", ½ ") are provided in our shop with measurements in mm. This may +-1mm, which is not a problem because the assembly is required for a hose clamp. If the hose is to be mounted without a clamp, it must choose a larger fitting. In some ports, which tend to deviate upward, it may be possible that such 13mm one actually does seal a tube with inner diameter of 13mm without a hose clamp.

Overview:
10mm (3 / 8 ") hose clamp: 8mm to none, from 10mm up required
10mm (7 / 16 ") hose clamp: 8mm to none, from 10mm up required
12mm (1 / 2 ") hose clamp: 11mm to none, from 12mm up required
13mm (1 / 2 ") hose clamp: 11mm to none, from 13mm required

Dimensions:
Outside diameter: 13mm
Inside diameter: 8.3 mm
Key width: 17mm
Thread Length: 8mm
Overall length: 37mm