Increase Gate Height for Larger Dogs 8 inch height extension by Cardinal Gates, the white Duragate Pet Gate Extension TPX-1 attaches to side of Duragate Dog Gate Model MG-25 not included . One side attaches through two openings in the TPX itself using a U bolt, the other side fastens around the side of the gate frame. Extends height of steel dog gate 8 inches. Duragate child safety gates in white or taupe can accommodate a 48 inch opening. Two top extensions per gate is the recommended maximum. Openings between bars are less than 3 inches high. For larger pets, you can install the pet gate 4 inches off the floor to add more height. Note Restrictive gates are recommended only for children up to 24 months. Taller or older children can use the gate extensions like ladder rungs to climb up and over the gates.