People in the lending business usually place a hold on your credit card for the full value of the item being rented until it is returned undamaged. The charge never actually hits the card unless something goes wrong.
When I worked at a hire company, we put a hold on the card for a fixed value for some smaller items - hand tools, things like lawnmowers that we were doing a deal on, or an extra days rent for larger items.
Although actually, the confidence I'm displaying above may be unwarranted. Maybe the hold value was actually a fraction of the full value and then a portion of the rental price went towards insurance. Not sure.