Offer Valid: 4/1/13 - 6/30/13 Buy 3 Herculite Ultra, Premise Universal or Premise Flowable refills, or Vertise Flow Refills, Get 1 Free! To receive your free goods, fax your Patterson invoice to 888-727-2614 or e-mail and attach a pdf of your proof of purchase to kerrpromo@kerrdental.com. Please print Promo Code N12 legibly on invoice. Offer cannot be combined with any other Kerr or Patterson special. Invoices received after 7/31/13 will not be honored.