In addition to picking the right material, you'll also need to choose a slide with the right safety features for your child. Slides can cause accidents even if they're placed indoors. For this reason, safety should be your top priority when buying a slide.
It's better if the slide has a platform with rails at the top so that your child feels safe once he/she reaches the top. This structure also allows your child to safely sit before sliding down.
For a secure landing, choose a slide with a flat surface at the bottom.
When placing the slide on the ground, make sure the ground surface isn't so hard and rough like pavement. Sand, grass, and wood chips are preferable outdoor surfaces for slides.
Additional safety features you should look for in a slide are slide bumpers and handles that are easy to grip.