Here are replacement portlight knobs (dogs) for the Bomar ports used on all True North Yachts. The are sold individually, with new screws and sealed washers. The larger ports require 3 dogs and the smaller ports require 2 dogs. This is a necessary replacement if your existing knobs are worn out, broken or the screws are damaged. We suggest replacing these when updating the gasket to ensure the entire system is updated at the same time.