Look for guardrails or handrails, rounded corners and splinter-free edges, anti-tip brackets or feet, non-slip pads on steps and bases, and construction from non-toxic materials.
Heights can vary and some platforms are adjustable (example platform heights listed at 10", 13.5", 16.5"); overall heights in examples run roughly from 24" to 35.43". Documented weight capacities in the examples range from about 110 lb up to 200 lb.
Electronic learning tablets in these examples use AA batteries (commonly 2 or 3 AA alkaline). Several non-electronic toys list no battery required.