Hose sealers seem to be typically sold in a combo pack with two types. When are garden-hose washers used and when are the O-rings appropriate? I've been kind of winging it with my own hoses, depending upon which seems to fit better. Is there more to the logic than that? Pictures would be particularly helpful.
Hose rings are flat to accommodate various types of male end connections. Some are cast brass, some are stamped from steel tubing. O-rings don't provide enough surface for the edges to press against. They're likely to slip past and be damaged or leak.
The two types aren't typically sold together because they're useful together. That's just another cheapskate ploy by retailers to save shelf space and sell you more than you need.
There are better washers than those large, flat, stiff rubber ones. The better ones are softer, a little smaller, and have three or so "ears" on them. I have never used an O-ring to connect garden hoses.
See these vinyl hose sealing washers with ears The washers are a little smaller than the large stiff rubber ones so they fit in the hose end easily, but the ears hold them in place. The old style may work for older extra heavy duty hoses which people don't buy anymore, but they are over-sized for modern "consumer grade" hoses.
No garden hose uses an O-ring for the junction between it and a threaded connection to something else. O-rings are only used with quick-connects that snap in and out.
Undersized cheap vinyl washers with ears are meant for cheap undersized hoses, are inferior to rubber and just save the manufacturer a few cents to make them. Before I bought any of those I would check the condition of the hose because it may not be in good enough shape to bother buying washers for.
Always get the correct size rubber washer when it is available.
The odd thing is that this question is asked at all. All hoses come with a washer so you should be replacing it with the same type it originally had in it.
We have one of the newer very flexible and light-weight garden hoses called "Zero-G" from "Teknor Apex" that will not work with the typical 1" diameter hose washer.
Oddly enough, the inner diameter of the female connector is 1 1/16 inches. If a normal 1" washer is used, it will leak.
To work properly, first a 1 1/16 O-ring has to be placed into the connector followed by a normal 1" diameter hose washer. The combination of the two work together to prevent leaking.
Amazing how foreign manufacturers can take something simple & easy that has worked for years and years and make it complicated with additional cost.