Forgot to mention that Aldi is selling a set of O-rings, came on sale last week, 32 different sizes, 420 O-Rings in total, from very small up to a couple of inches. It does not state what they are made from but it looks like latex or silicone. This is the best O-Ring set I have ever bought and about the 4th from Aldi, only £3.99. You should easily find an O Ring to fit alarms, banksticks, fuel bottles etc, They would even do probably to attach to your belt or jacket for carrying torches, forceps etc and even to replace seals in water containers etc in this set.

Why I needed another, I don't know, just a "Mans Thing" I presume.

Also in the same sale they are selling a set of "Fibre Seals" for the likes of tap and hose washers etc, they may fit some alarms and be more durable than the O Rings. Same price

They still had loads in stock yesterday.