A Letterbox Hybrid cache is similar to a traditional, but has a stamp, and in this case a 'pig'mentation ink pad inside so that you can visit them and add the stamp's picture to your notebook.
This harks back to the similar hobby back in Victorian days.
Please leave the stamp and the pad inside the cache, they are not swaps and are an integral part of this game. The stamp is also inside a plastic bag to protect the rest of the contents of the cache.
This cache has a slightly contrived name, and will be near a few similarly-named pig-related caches, and it will hopefully make a little more sense once they are out. Pad being another name for 'house' particularly, 'sty' or 'pen'.
I hope you enjoy finding this cache.