From MAGPUL:  The SGA Stock is an ambidextrous, user-configurable buttstock designed to add much-needed adjustability to the tried-and-true Mossberg 500 / 590 / 590A1 12-gauge series of shotguns. Its features include a spacer system for length of...

Side Saddle/Universal Q-DC The Universal Q-DC is compatible with most pump action and semi-auto shotguns. Due to the trigger assembly pins and the shape of the Universal Receiver Adapter, it is not recommended for Remington 870s or the Mossberg 500/590...