Many customers ask this question! It's the width and depth of the putter grip which is denoted by the two numbers in the title. For example, The Snug Daddy 24 is 24mm wide and 24 mm deep whereas the Snug Daddy 33 is 33mm wide and 33mm deep. As a result of feedback from tour professionals we introduced our Snug Daddy 27W which is actually 30mm wide and 27mm deep. Many tour professionals really liked the depth of the grip but found that a slightly wide profile further reduced any potential grip twist.