The AB40 Horizontal Adapter serves as a horizontal adapter for the MM340, MM540 and MM700 mounts, providing a 90-degree bridge between their wall plate and the TV mount lifting arm.
MantelMount Thin TV Gap Spacer
TVs that are super thin up top but thicker at the bottom and with very low mounting holes tend to wobble when positioning the TV to the desired viewing angle. This is common with many OLED TVs, and most notably LG OLED TVs, no matter TV mounts they are paired with. The GS60 Thin TV Gap Spacer stabilizes the back of these super thin TVs by providing the extra upper support needed. 
Features
Used to prevent wobbling for TV's that are thin at the top, wide at the bottom and with very low mounting holes.
Most common with OLED TV's especially with LG OLED TV's.