New Dog! Neck collar?

[ChargingCatcher]

Check him out! Took him out yesterday, trailed and caught at a year old. Boxer X Greyhound. I am really seeing these Bully Lurcher crosses are where its at.
75 pounds of nothing but muscle, can keep up with my mountain bike at over 25 mph with ease, has a nice hot nose and a drive and grit that to beat!
Now the thing is in measuring I am not sure whether his neck is a 4.0 or a 4.5
I dont want to get anything under or over sized, he is in the middle.

[halfbreed]

catcher you figure out that dogs neck yet ? if you want to be sure just cut some carboard strips and see whats best thats how i did it when making my collars