Every 'Mech supports three types of internal cockpit items: Standing, Hanging and Mounted. These are all cosmetic only; they do not give any in-game advantage or enhancement. However, some provide XP or C-Bill bonuses or increased Faction Reputation. Some are simply holiday decorations.
Each item has a unique position within the cockpit, which may change depending on which 'Mech chassis you are placing it in. The Cockpit item Warehouse is filtered by Standing, Handing and Mounted, and can be further filtered on "All", "Owned" and "Sale". Many include sounds and movement - select the "preview" button to see the animation or hear the sound.
Within the select item window the lower left hex resets to the last saved item and the lower right hex removes the item.
Cup of coffee, ice cream sundae or a bottle of the Inner Sphere's finest bubbly (2395 - a very good year). Some items bobble with movement, some are continuously animated, some jump out of a trash can with every kill!
Hang your dog tags, contemplate your faction's dream catcher or just stick your duct tape. Most sway with 'Mech movement.
Place holiday lights around your cockpit or mount a war horn. Announce your success with every kill - get those bag pipes howling!