Chris Christensen Mini T-Brush - 12, 27mm

Do I get a 16 or 27 mm for my Golden retriever?

What type of warranty against workmanship defects does this carry? Purchased mine in May2018 and the brush head just came off the handle.

Is this the same as the A414 rake brush?

Do the bristles have a round protector tips at the end? I'm using it for something other than use on a pet so I don't want the rounded tips.