I have a 5" Strikemaster Lazer and turning effort is quite a bit less than my 6". I highly recommend going with the Normark Finbore in 4.5". I have a 6" Finbore and love it, I am picking up a 4.5" Finbore this season. The Finbore is a fast auger, has replaceable blades and a folding offset handle. Fish307 should have them in stock after while.