Star Trek: The Original Series, Dr McCoy's Hypospray Mk II

replica movie prop

This is the second style of hypospray seen on Star Trek: TOS; appearing in the second and third seasons. Unlike the previous "sleeve" incarnation, this version features a telescoping plunger-style movement reminiscent of a modern hypodermic needle. This replica is machined aluminum with interchangeable glass vials of pseudo medications (attached with velcro). I have been told that this appears to be the work of the late Steve Horsch but I cannot confirm this.

More from Memory Alpha:

A hypospray (colloquially, hypo) is a medical device used to inject liquids into the body. The system uses a noninvasive transport mechanism of compressed air to transfer the injectant from the device into the subdermal layer below the skin of the body, or artery. This is done without the use of a needle, ensuring that the skin is not punctured during use, thus reducing the risk of infection or pain at the site of injection. Various drugs can be used, inserted into the hypo in vials attached to the end of the instrument.