Offer Valid: 4/1/13 - 9/30/13 Buy any 3 Tray Items, Get 1 Free! Promo Code 1829. To receive your free goods send a copy of your Patterson invoice to GC America Inc., Attn: Customer Care Group, 3737 West 127th Street, Alsip, IL 60803 or fax to 800-423-2963. Cannot be combined with any other promotional offers. Free goods will be of equal or lesser value to the lowest selling unit price. No substitutions allowed. Offer valid in US only.