The Seagull 4A-109 TLR was designed and produced by the Shanghai General Camera factory – located in Song Jiang county in the Peoples Republic of China. It is a fully manual medium format twin lens reflex camera.

The 4A-109 has two fixed lenses, the bottom one is used for taking the image, and the the top one is used for composing the image and focusing on a fresnel screen at the top of the body, inside the fold up hood.

The taking lens is a 75mm Haiou SA-99 with a maximum aperture of f3.5, the top viewing lens is also a 75mm Haiou SA-99 but it has a fixed aperture of f2.8. Due to the camera using an leaf shutter inside the lens assembly, it can synchronise with a flashgun at any speed, up to and including the cameras fastest shutter speed of 1/500th of a second, making it very adaptable for flash photography.