Developed from the Proton Grenade (Air Filter Prototype), Proton Grenade (Test Tubes)'s were not utilized until later as an alternative to Proton Grenade (Air Filter). Three Proton Grenades were stored on an ammo shoulder strap before the Ghostbusters departed for The Mercado Hotel. They were used by Holtzmann against several ghosts in the Times Square battle.
- ↑ Deutsch, Stacia (June 2016). "Ghostbusters Movie Novelization", p. 117. Simon & Schuster Children's Publishing Division, New York NY USA, ISBN 1481475126. Narrator says: "Patty threw proton grenades, sending several ghosts flying in another explosion of ectoplasm."
- ↑ Holder, Nancy (July 2016). Ghostbusters, p. 237. Tom Doherty Associates, LLC, New York NY USA, ISBN 076538843X. Narrator says: "Holtzmann had also created two kinds of grenades--'air filters' and 'test tubes'-- plus a proton grenade launcher for Erin and a 'drop-down' gun for herself."