Like Mmckenna has mentioned, they are good to pack in a "to go kit" for use in an adaptation mode. The big square magnets, have a rubber boot around the edges, while the circular does not. The circular will scratch the cars finish while removing it while the Larsen square, with rubber edges seems to not scarch on removal. Really never noticed much difference in transmit range over the trunk lid mount vs the mag mt. Mag mt on the roof, again not much difference between a hole mt vs the mag mt. Over time, on a mag mt roof mounted, the wind beats the cord to the point the cord will break and the vibration of the cord leaves scratches on the paint. Mag mt on the trunk , the cord can be routed through the back seat and the cord seems to last as long as a trunk lid mt cord. Mag mts are good when you have to take the car through a car wash They are quicker than having to unscrew the antenna from a nmo trunk lid mt..