The boxes are all 12″ tall, the height of the opening is 6″ on the 24″, 6.5″ on the 30″ and 7″ on the 36″
All sizes are complete with puppy rails
The advice we give when selecting the correct size box is to measure the bitch from nose to base of tail add several inches for poles and free room and then go for the next size box up. (This is advice only and is ultimately down to the customer to select the correct size)
All sizes quoted are approximate dimensions.