Medium Heavy Duty Deadbolts This Yale series is the ideal commercial grade deadbolt for use with Yale knob or door lever sets in heavy duty residential, medium duty commercial or intuitional applications. 8411 - Yale 8400 Series Medium Heavy Duty Deadbolt (Cylinder and Thumbturn) 8411D - Yale 8400 Series Medium Heavy Duty Deadbolt (Cylinder and Thumbturns with Dimple Key) 8421 - Yale 8400 Series Medium Heavy Duty Deadbolt (Double Cylinder) 8421D - Yale 8400 Series Medium Heavy Duty Deadbolt (Double Cylinder with Dimple Key) 8211 - Yale 8200 Series Medium Duty Deadbolt (Cylinder and Thumbturn) 8211D - Yale 8200 Series Medium Duty Deadbolt (Cylinder and Thumbturns with Dimple Key) 8221 - Yale 8200 Series Medium Duty Deadbolt (Double Cylinder) 8221D - Yale 8200 Series Medium Duty Deadbolt (Double Cylinder with Dimple Key)