Since the time I played in The Nashville Symphony I have kept a mute in the back of the car.
The idea is that if you forget to bring your better mutes you will always have a mute of some sort to get by with in a pinch. Back then the original mute I owned, the standard Stone-Lined horn mute, was the car mute, such as the one seen here.
Yesterday I made use of the current car mute, as I left my better mutes in my office by accident. My car mute is a Stone-Lined “Rittich-style” mute (the one that is a tall cone). My favorite mute (which I will use today) is an actual Rittich mute, one made by the late Eugene Rittich, who was for many years Principal Hornist of the Toronto Symphony Orchestra. These are no longer manufactured; among my students the most popular options are Ion Balu and TrumCor.