Sony 364 (SR621SW) 1.55V Silver Oxide 0% Hg Mercury Free Watch Battery (5 Batteries)

I got this battery for my Skagen watch which finally stopped ticking because of the battery. I had purchased a watch repair kit from Amazon already and just needed a new battery.The batteries arrived in perfect condition, and also had an strip of anti-static strip wrapped around them probably to prevent any damage from electrostatic but most likely it was in the packaging by mistake. This order comes as a pack of 5 batteries and at the back there are round perforations behind each battery that makes it easy to take battery out without tearing the whole packaging apart.The print on the package specifies that I can use it until 04/2020 which his around after 2 years of the purchase in my case.This is a silver oxide battery which usually have high energy-to-weight ratio, which means they provide lot of energy relative to their weight as compared to alkaline batteries. Though lithium batteries have higher energy density than Silver oxide and Alkaline. Silver oxide batteries used to contain a little bit of mercury which would cause issues if they leaked. Sony was the first manufacturer to make Mercury free silver oxide batteries. Most of the silver oxide these days are mercury free (atleast from well known brands.)Another characteristic that silver-oxide batteries have is that they have flat discharge curve, which means that these provide near constant voltage until they discharge quickly over a short time instead of gradually discharging over a long time. So they are quite suitable for stuff like watches that need accuracy instead of gradually slowing down over a long period.Silver oxide batteries are usually of 1.5V (and so is this one) while lithium-ion batteries are usually 3.3V. Also, these lost longer than alkaline and are also easier to recycle.WHAT IS SR621SWInternational Electrotechnical Commission (IEC) assigns each type of battery a code, which is described in IEC 60086 document. The code for this battery is SR621SW which comprises of S,R,6,21, SW. Each of these has a significance as following:S - specifies that this is a Silver Oxide batteryR - Specifies the shape which in this case is Round. Other shapes are Flat (F), Square (S), and Not Round (P)6 - specifies the truncated value of diameter in millimeters. The Sony spec for this battery specifies the diameter for this battery is 6.8mm21 - specifies the height of the battery in tenths of millimeters. The height of this battery is 2.1 mm.SW - means this battery is for low drain devices as opposed to high drain devices that end in W instead of SW. Low drain devices are watches which do not require much power.CAN THIS BATTERY REPLACE ANY SILVER-OXIDE COIN BATTERYProbably not, unless it is of the same dimensions. First important thing about this battery is the dimensions (which is 6.8 mm diameter and 2.1 mm height.) If the battery you are trying to replace has same dimensions and is also a Silver Oxide battery then you may be able to replace some other battery with this one.Several manufacturers sell the SR621SW battery with their own codes e.g. 364 (Energizer), SR621SW (Sony, Maxell, Panasonic), D364 (Duracell), T (Timex), 280-34 (Citizen), SB-AG/DG (Seiko). They should mention the IEC code and you should be able to use them if they are of the same code.

batteries were fine

Ordering again as a number of watches use this battery. Sony is a brand name for expected long life as I've now replace the battery in 3 different watches. The price is right for a 5 pack as single battery purchase is much more expensive. Rated 4 stars only because battery life not yet determined, possibly a 5 star purchase.

The Sony battery originally installed in my wife's Fossil analog wristwatch failed after roughly two years of use... can't complain about that longevity. So, I figured I'd look for Sony's to replace the battery originally in the watch. After looking in big box stores and drug stores in the area and finding that one of the batteries sold for roughly $5, I thought about checking trusty old Amazon for better deals. Sure enough, there was one. Unfortunately, it's hard to tell anymore whether batteries you receive are the real deal or fakes. While I can't confirm with absolute certainty these are 100% legit, I can offer the following based on installing one battery and my wife using the watch for a week (I know, I know... that's not all that long), but please read on.Pros: Short of the great price on these batteries (sometimes things are too good to be true), there were no red flags to be seen on the battery housing or on the packaging. If these are fakes, then those who faked them are true masters of forgery. The branding, etc. on the battery matched the one that came from my wife's watch in every way. The battery was exactly the same circumference, height, build, etc. as the original. In addition, the instructions, etc. on the blister pack in which the batteries came was perfect. The English was spot on (it usually isn't in fakes... I've seen my share in purchases from some shiftier vendors), the use by date seemed right (07-2019), labeling was good -- overall, the packaging just seemed legit. Another pro (the biggest, of course) was the battery fit my wife's watch with no issue and got it working immediately upon install. She was elated, as this watch is her daily driver and she can't live without it. Since she was happy, so was I.Cons: None so far.Recommended Purchase?: I know only a week's worth of use isn't really a great indicator of whether someone should consider purchasing a battery or not. Really, the saying, only time will tell, seems very fitting given the battery will be used in a watch. For now, since there was nothing suspicious about the battery or the packaging, and since my wife's watch is once again working... I have zero reservations recommending the purchase of these batteries. If I have a reason to change the review (for better or worse), I'll do so ASAP.

I am satisfied with this product as advertised on the web. Thank you

Fine

Batteries are for a watch, fit perfect, won't know about longevity yet.

This review is for the Sony SR621SW 1.55V Silver Oxide Battery (5pcs per pack).Recently I decided to purchase all of the tools necessary to replace my own watch batteries and stop getting ripped off by the jewelry stores and mall kiosks. After I receive the tools, popped open the watch backs, I made notes of all the batteries I needed and ordered them. The cost for a 5 pack of batteries was less than what one battery would have cost me from a jeweler or mall kiosk. It definitely pays to change these out yourself! And now I have extras as well!A fabulous buy!