The Priority Mail Medium Flat Rate Box features predetermined rates regardless of weight (domestic only).

• USPS SKUs:
• Priority Mail Medium Flat Rate Box (11 1/4" x 8 3/4" x 6"): O-FRB1
• Priority Mail Medium Flat Rate Box (12" x 3 1/2" x 14"): O-FRB2
• This product is free and will ship separately with no shipping charge
• Call 1-800-610-8734 for orders exceeding the maximum allowable order size