Why do KNOCKDOWN™ Series targets cost less than BOUNCEBACK™ Series targets?

KNOCKDOWN™ Series Target are roughly half the thickness of BOUNCEBACK™ Series targets because the bullet only needs to knock the target over-center to knock it down. BOUNCEBACK™ Series targets are made thicker because the bullet has to "hang-on" to the thickness of the target a little longer in order to cause its snap-back action.