Durability: My toddler has chewed on a few and they still seem to work great. I've stepped on a few and the prongs did not bend. We have these all around the house on multiple different types of outlets and they fit everywhere.
They are very easy to slide on. I hate having to remove them from an outlet because it is sometimes hard to remove! This is great for a toddler and horrible for an adult trying to plug in something quickly. The purpose of these is toddler safety, so they do the job. I attached a video on an outlet that is not hard to remove, I think there might be small differences in the product or outlets which cause the fluctuation in strength to remove.
Swallowing: they are decently big, it would be hard to swallow for a child under 1 in my opinion.
Overall: This outlet cover will protect your child. They make me feel like a good parent when I see a covered outlet. Some will be hard to remove from the outlet, others will not be as hard, they are very durable. Tip: Count how many outlets you have, subtract the ones you