From Polaroid Swinger Model 20 | Camerapedia | Fandom:
Typical elements of simple box cameras were combined in the Polaroid Swinger Model 20: a non-focusable meniscus lens (Polaroid f17 100mm), a simple rotary single-speed shutter (1/200 sec.), and last not least roll film as media, the first type of roll film for exposures which had to be pulled out of the camera to be developed in the light. The Polaroid film designed exclusively for use with the Swinger (Type 20) had the same very fast (EI 3000) emulsion as the extant film types 37, 47, 57 and 107. The camera was called the model 20 because the original goal was to create a camera that cost around $20.
Other features were a telescopic viewfinder, an AG-1 flash-bulb socket with reflector hidden behind the meter window, and a red aperture control thumb wheel around the long shutter release button, combined with a flash range scale. A simple meter controlled feature was the sign "YES" that appeared in the window under the finder ocular when light and aperture were sufficient.
It was an early one of the very cheap instant camera models of Polaroid, made from 1965 to 1970 in the USA and in England. Its earliest version was made in the US, with additional "NO" sign for insufficient light situations.