Toddler Learning Stool - Are they safe?

[organicoatmilk]

I'm thinking about getting one of these for 18 month old. I'm just a bit concerned they aren't safe and that they'd fall backwards on it. Has anyone got one and can tell me what they're like? Thank you.

We have one at work that is like an enclosed box that you lift the child into. It's very stable, the two year old tried to climb in himself and it doesn't tip up.

It's this little helper one.