Mars Coat KingTriple Wide For Horses, 60 Blades, Extra Fine

I have a golden retriever with a very thick top coat and under coat. i tried the 20 blade and it just didn't do the job. would this 36 heavy coat do j

What size would I need for a horse that’s not shedding. 30 or 60. What is the difference in the two?

How long is the head of the coat rake?