Based on this product's specifications, here are some alternatives and similar models
Pressure-reducing pad Matex Paddi’x for car seats 0–13 kg & 18–36 kg
Summary description:
Matex Paddi’x pressure-reducing pad is an accessory for infant and child car seats sized for 0–13 kg and 18–36 kg groups. Designed to redistribute pressure and increase comfort, the pad is used as an additional cushioning layer between the child and the seat surface. Suitable for daily travel, long drives and improving fit in compatible car seats.