Many modern fire alarm pull stations are single action and only require the user to pull down the handle to sound the alarm. Other fire alarm pull stations are dual-action, and as such require the user to perform a second task before pulling down, such as lifting up or pushing in a panel on the station or shattering a glass panel with an attached hammer. Perhaps the most recognizable pull station is the "T-bar"-style pull station, so named because the handle is shaped like the letter "T". This style is manufactured by many companies, most notably SimplexGrinnell.