The Multifunction Device was a handheld device Egon Spengler used to perform a number of tasks.
After the Ghostbusters and Slimer safely extracted the Stay Puft Marshmallow Man, Egon used the Multifunction Device to remotely reverse the polarity of the Trap that held him.  Stay Puft was released along with Slimer and Phantom. Egon then used the device to emit a homing signal that would help lead Stay Puft to Battery Park to shoot a commercial. When Phantom proved too be too distracting, Egon quickly modified the device to emit an even stronger signal. 
- On page two of Ghostbusters Issue #11, the Multifunction Device makes a non-canon cameo used by Egon Spengler.
- ↑ Egon Spengler (2009). The Real Ghostbusters - "Sticky Business" (1987) (DVD ts. 08:38-08:41). Time Life Entertainment. Egon says: "Stand by. I'm reversing the polarity on the Trap."
- ↑ Peter Venkman (2009). The Real Ghostbusters - "Sticky Business" (1987) (DVD ts. 15:14-15:16). Time Life Entertainment. Peter says: "How long before that Stay Puft leash is fixed, Egon?"