This is a sturdy aluminum straight mute designed to fit all bass trombones. It is made in the USA by Joral and is available in three versions.
The standard model is all aluminum. It's slightly heavier than Denis WIck and Tom Crown straight mutes, the cork is thin enough for a good fit without filing, but thick enough to allow some volume when you push it.
Also available is the aluminum mute with brass bottom. This one seems to have less edge, a warmer sound, somewhat less offensive. It feels heavier.
The last version has the copper bottom. This mute has more sizzle to the tone when you push it, but still has a fairly deep tone. It's not tinny but has a more obvious mute buzz.
Some players may simply need all three. 188g