Duracell 399/395 Silver Oxide Battery (SR927)

This is a single 1.5V silver oxide coin cell, the size usually listed as 399 or 395 and coded SR927. One cell answers to a long string of part numbers, and the card prints them all: 399, 395, V395, V399, SR57, SR927W and SR927WS. If the battery you have taken out shows any one of those, this is the replacement. It comes on a Duracell blister card with the cell held behind a clear window, so the code stays readable until the moment you press it out.

Silver oxide is the chemistry the watch trade settled on. A silver oxide cell holds a nearly flat voltage across most of its working life instead of sagging steadily as it drains, which is what a quartz movement wants if it is to keep time to the same accuracy in month twelve as in month one. That makes cells of this type the usual choice for analogue quartz watches, and they turn up too in small clocks, calculators, laser pointers, thermometers and other low drain electronics that need a stable 1.5V from something the size of a shirt button.

One unit of this listing is one cell, so order a unit for each device you are fitting rather than assuming a strip. The minimum order is 10, sold in multiples of 10, which makes more sense for a repair bench or a counter drawer than for a single watch. It sits alongside our other Duracell silver oxide cells in SR621, SR920 and SR626, the lithium coin sizes CR1616, CR2016 and CR2032, and LR44 in alkaline. The card carries a keep out of reach of children warning, and a cell this small is easy to swallow, so store spares and spent cells where children cannot get to them.

Is SR927 the same battery as 399 and 395?

Yes. SR927 is the code printed on this card, and 399 and 395 are the two designations the same cell is commonly sold under, so all three point to one battery.

My watch back is marked SR57 or SR927W, will this work?

Those are both listed on the card as alternative codes for this cell, along with V395, V399 and SR927WS, so a device asking for any of them takes this one.

How many cells do I actually receive?

One unit of this listing is a single cell on a single card. The minimum order of 10 means ten of those cards, so ten separate cells rather than one pack of ten.

Which way round does the cell fit?

On a coin cell the large flat branded face is the positive terminal and the rim is negative. Most watch and calculator holders want that branded face upward, but check your own device first.