Feature: The ideal solution for many cameras such as the Olympus OM1, Rollei 35, Yashica 124G, etc that used the original PX625 (1.35V) battery. (But will not fit Leica M5) Today's equivalent to the PX625 battery is the "PX625U". It is the same size and shape, but the voltage is 1.55v - which means that the battery will give an "over-voltage" and would give incorrect meter readings. One of the solutions is to use a Weincell PX625 Battery, however zinc air batteries only last a few months once they are activated. So is there another solution? Yes - fit this adapter (which is the same shape as the PX625 battery) into the battery terminal of your camera and power it using a "Zinc Air 1.4v battery" - the 1.4v Zinc air battery (which is shaped like a standard LR44 battery) can be purchased from various sources. The zinc air battery is known as 675 battery (aka: hearing aid batteries). The adapter is precision made. Please note: the listing is for the adapter only - the "1.4v zinc air batteries" can be found online from a number of sources (Image shows original PX625 battery against adapter and Yashica 124G - both of which are not included). Q: Will this convert the voltage of a battery? A: No - the adapter will not convert a voltage - it only converts the physical size of the battery. Q: Is there an adapter made that converts voltage? A: Yes, there is an adapter made with a small micro chip - however, they are not too reliable - they work fine at the beginning, but after a few uses they start to give intermittent problems with the voltage. Our adapter has no chip, so it is much more reliable - and still gives the correct reading! (When using zinc air battery). Q: So what battery do I need? A: You will require a Zinc Air 1.4v battery - which is known as a 675 (often referred to as a hearing aid battery). Name: Battery Converter Adapter. Packing List: 1 x Battery Converter Adapter (Battery is not included).