Determining dog size for the K9 Sport Sack is not rocket science. If your dog is in between sizes, has a wide frame but little length, or is still growing - the Booster Block Backpack Pad fits comfortably in the bottom of the K9 Sport Sack and raises your dog's position by 7.62 cm. It also helps make both you and your dog more comfortable when using the K9 Sport Sack Booster.

• made of strong and high-quality foam
• removable, washable fabric cover
• using two blocks to raise 15.24 cm