Pentik's cushion inserts are sized precisely for Pentik's cushion covers. It's best to choose a cushion insert that is slightly larger than the cushion cover to make the cushion look invitingly plump. A larger 48x48 cm insert is suitable for a 45x45 cm cushion cover, and a smaller 45x45 cm insert fits 43x43 cm cushion covers. A 43x63 cm insert is suitable for 40x60 cm cushion covers.