Based on this product's specifications, here are some alternatives and similar models
Adapter/Reducer ARMAKAN 50/40 5770541 — pipe transition 50 mm to 40 mm
Summary description:
ARMAKAN adapter/reducer 50/40 (model 5770541) provides a secure transition between a 50 mm and a 40 mm pipe. Designed for plumbing and ventilation systems, it facilitates connection of different-diameter pipes, ensuring proper fit and leak-free joints when used with compatible materials. Suitable for installers and DIY projects requiring reliable diameter reduction.