From the specifications provided,
http://www.walmart.com/ip/Combi-Kobuk-Air-Thru-Booster-Seat-Licorice/15902654#about
Combi Kobuk Air-Thru Booster Seat
-Designed to accommodate a child 3 years and up, from 33-125 lbs and 33-57"
-Converts from a highback to a backless booster
-Integrated padded armrests
-Removable cup holder for left side or right side
-Removable and washable fabric cover
-Dimensions: 17.5"L x 19"W x 25.5"H
-Dimensions without back: 17.5"L x 15.75"W x 9.5"H
-Product weight: 9.5 lbs
-Product weight without back: 4.62 lbs
This combi brand booster seat seems quite comfortable with the features of the height adjustable backrest, armrests and removable cup holder of this Backless. It can be used as a highback or as a backless booster, keeping your child safe after he or she out-grows a car seat, which is a plus point as you do not need to buy another backless booster seat when your child is older.