The stun gun props (see Continuity Guide) vary in detail. A kill-stun slider added to some props in The Full Circle. In addition to these "hero" props, many vacuum-formed molds were created. These were molded over a hero prop, making a slightly larger prop with more rounded edges and buttons. The black finger grip is flat and featureless, and the central seam is more prominent than the hero version.
Keith Wilson's original design drawing from 1973. The original concept by George Bellak and Christopher Penfold was for a multi-purpose hand weapon with four antennae: tranquilliser, stun, laser, atomic, hence the initials "TSLA".
This is an original vacuum formed prop.
The original vacuum-formed prop compared to a modern replica of a hero prop.
After the series, Tony Anholt gave his prop commlock and stun gun to his young son Christien as toys. In 2024, Christien bought the props to the London: 1999 convention. The props are a little battered from years of play (and probably took some battering in the studio during filming).
The prop in Tony's holster in Immunity Syndrome. Later in the episode he has the "hero" prop with stun/kill slider that Lustig is holding in this shot.
The prop is vacuum formed and very light. It has been repainted in silver paint (perhaps young Christien was inspired by the Remco-Burbank stun gun, and anticipated the Sixteen 12 stun gun). The detailing is softer and more rounded than the vacuum formed prop above, as if it was vacuum formed from the other vacuum formed prop.
Thanks to James Winch.