Collars
To measure for a collar
Take two capenter squares place them together to form a "C". 
Place the top of the "C" in front of the withers (closer to the mane), place the bottom of the "C" two inches in front of the shorlders (point of shoulders)
Put the measuring device on as if it were half of a collar, with the top right where the collar should lie at the base of the neck and bottom right below their throat to avoid airway constriction.
Measure the inside of the "C" to obtain the size.
Measure the inside of the "C" to obtain the size.
