Where do i purchase damage insurance for weekly rentals?

i've been charging a refundable $500 damage deposit but i'm getting a sense people don't like it even though they get it back. i've seen tons of people on vrbo charging $50-$85 for a non refundable damage deposit thats no refundable. i'm thinking thats much easier to sell. does anyone have the names of co's that provide that insurance and how it works? thanks