This is the “Heym” pop-out air pistol. It was manufactured by F. W. Heym GmbH & Co. K.G. of Münnerstadt in Germany from 1949 to circa 1956. According to the The Encyclopedia of Spring Air Pistols, it is said that approximately 1,500 of these air pistols were manufactured between 1949 and 1952. That’s not a lot in the grand scheme of things which makes this a pretty rare air pistol to find today. 
The frame of the pistol is made from cast alloy and the .177 calibre barrel is smoothbore steel. The plastic chequered grips can be either mottled white/brown or black. The body of the pistol is usually finished in black enamel although this particular pistol has been finished with black crinkle paint. I am not certain if this is an original finish though as I have not seen any others with the same crinkle finish. Having said that, there’s not many documented examples anyway!
The company was originally founded in Suhl, Germany by Friedrich Wilhelm Heym in July of 1865. The company produced hunting guns and on May 24th 1891, Heym was granted patent No. 60215 for a triple barreled hunting rifle which had three triggers and three hammers on the same axis. The company expanded to produce barrels, shotguns and under-rifle combination shotguns with Russia their major export market until 1914. 
The company remained under the management of various Heym family members until 1988 when Oskar W. Zurflüh became the manager. Similar to many gun making German companies following the war, the company was re-established in West Germany making cuckoo clocks, slide rules, spinning wheels and various other non-firearm products until the restriction of production of weapons was lifted. 
Interestingly, back in 1835 in Suhl, there were apparently 16 men with the name Heym that worked on guns! By 1895 the list had grown to 25 Heyms that were either gunsmiths or stock makers! 
The company still exists today as Heym AG and continues to produce handcrafted, high quality, luxurious shotguns and rifles. 
During its entire existence, Heym produced just three airguns in all. These were the LP101 and LG102 air rifles and the Heym LP103 air pistol. 
Until next time, happy shooting!