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K9 Sport Sack

K9 Booster Block

$9.95 $9.95

Sizing your dog for a K9 Sport Sack® isn't an exact science. If your dog is in between sizes, has a wide body but short in length, or is still growing, the Booster Block fits snuggly in the bottom of your K9 Sport Sack to boost your dog up 3" (7.62 cm). It helps make the K9 Sport Sack experience more comfortable for you and your dog. 

  • Constructed of sturdy, quality foam
  • Removable, washable cloth cover
  • Use two blocks for a 6" lift
  • XS/S measures 3" tall * 8" wide * 5" deep (7.62 cm * 20.32 cm * 12.7 cm)
  • XS/S are interchangeable between XS and S sized backpacks
  • M/L measures 3" tall * 10" wide * 6" deep (7.62 cm * 25.4 cm * 15.24 cm)
  • M/L are interchangeable between M and L sized backpacks and are also compatible with XL and XXL if necessary
Shipping, Warranty & Returns


Domestic orders: A variety of UPS shipping methods are available. Please allow for 1-2 days of packaging before your item ships, 2-5 days if ordering a waterproofed or custom item.

International orders: UPS Worldwide Expedited shipping (average delivery in 3-5 days, but varies depending on location).

For more information regarding shipping click here.


We cover manufacturers defects and product malfunctions for the first 60 days (Excludes klearance and custom items). Learn more about our policy here.


If you end up with incorrect sizing don't worry! All size exchanges within 60 days are free excluding original shipping costs (Also excludes klearance and custom items). Learn more about our policy here.

Customer Reviews

Based on 107 reviews
Just get it

If you have a small dog,senior dog, or a just want your fur baby to be comfortable when in this…get it. Those few inches that it gives helps with comfort for you and the pup. It gives them the option to sit like on the couch or in a seat.

Terrie Correnti

Could not be happier. Leroy loves his pack, he turns into a puppy when we get his gear out because he knows he's going on a adventure. He turns into a little diva when his picture is taken.

Augustine Hernandez Jr
Works like a charm

The booster was exactly what we needed for our dog was right in the middle of the pack sizes.

The booster allowed our dog to have his front shoulders out through the shoulder holes better. In addition, it allowed him to sit up higher and look left and right of my head.

Glenn Schiffbauer
Lucy in her K9

Lucy is a great hiking passenger.

william Presley
Optional Cushion

We have a Cavalier King Charles and found the small backpack was a little too large. We purchased a cushion and now he fits perfectly in the Backpack.