Pin lock homebrew kegs were used exclusively by the Coca Cola Company and utilize a pin lock style disconnect to connect and disconnect to the liquid and gas lines. Many people love these kegs for their affordability, availability, and that it's literally impossible for you to connect the wrong disconnect to the wrong post. Liquid posts and pin lock liquid disconnects will only fit each other while gas posts and pin lock gas disconnects will only fit each other too. It makes it easier to not accidentally put your gas line on your liquid line in case you're a little tipsy from enjoying your brews (totally not a real story about this happening to any of us!). Pin lock kegs are also shorter, yet wider, than ball lock kegs which is appropriate for some people's situation if you need that top clearance due to limited space in your kegerator or keezer.