Cold & Flu: First Years

First Years Compass Booster Seat

I am looking for a first years compass b540 booster carseat . They have them everywhere for sale online but I want to see it before I buy it. I have called Target, Walmart, Lonestar baby, babies rus and burlington coat factory. Anywhere else they sell car seats that I may have missed? Is this a good booster seat? My daughter is 4 y.o. 58lbs and 44" tall. She is using a Britax marathon now and can barley buckle her with a jacket on.