We will combine shipments for up to 5 back side sets at a time. Please contact us if you wish to combine shipments. Shipping costs will be based on weight. In some cases we may have to manually adjust the shipping costs for you. We will also combine smaller items such as Fret boards and Bridge Blanks. We use UPS for domestic shipping and USPS for international shipping, regardless of the shipping option you pick. Please contact us with any special shipping requests and we will do our best to accommodate you.