Car baby alert

Safety for children is the first thing to be respected!!!! I designed this car accessory to avoid (at least an additional warning to the driver of the car) to leave a child on board and avoid the worst. For the operation of the gadget you need a compression spring with an external diameter 5x50 (see link below)JINGERL 10pcs Molla a Compressione del Filo in Acciaio Inossidabile, Diametro del Filo da 0,8 mm * Diametro di 5 mm * (5-50) mm Lunghezza (Size : 0.8x5x10mm) : Amazon.it: Commercio, Industria e Scienza AFTER INSERTING THE SPRING, CLOSE WITH THE BACK PIECE (IF YOU WANT YOU CAN GLUE OR ADD DOUBLE-SIDED TAPE SO AS NOT TO HAVE PROBLEMS WHILE DRIVING) The functionality (obviously mechanical and not electronic) is very simple:Attach the gadget to