The Extra Tall Free Standing Gates are 36" tall. The only gate we have that can reach about 45.5 inches in height is the Duragate (PETCO SKU # 1309544) with two (2) height extensions (PETCO SKU #1309722) installed. Two is the max number of height extensions recommended for this wall-mounted gate.
Depending on your dog's breed and whether there are children in the home, you might be able to install the gate a bit higher to reach the 48" you need. Hope this helps! The included photo shows this gate with the height extensions.
Duragate with 2 height extensions - 45.5 inches tall
Duragate with 1 height extension = 37.5 inches tall