Marco TIME Mainspring #4083 for Looping Clock Model 50/51 - Steel

Marco Mainspring No. 4083 TIME side Mainspring suitable for Looping Model 50/51 Travel Clocks the 1930's and beyond, tongue end, steel, new in envelope. Could also very well fit in other travel & alarm clocks. I likely have several of these so the one you get may differ slightly from the images. See image for precise mainspring characteristics. Images do a suitable job of representing the item.