A dark colored, thick viscous oil derived from chopped and then sun rendered beaver tails.  It has an evenly pronounced aroma with a consistency of about 80 weight motor oil.  BTO is great curiosity ingredient in lure and bait formulatioins, or it can be used in a dirt hole set by itself.  It is a great addition to any canine set.  Canines will display an aggressive digging reaction at the set.