These fit simplehuman trash cans really well. You can use other trash bags with those cans of course, but you'll have to spend an extra 30 seconds tucking the bag in properly, or it will fall into the can. These will save you that amount of time. Unlike some other drawstring bags, these drawstrings will completely close the bag. These seem very durable, although I haven't pushed them to their limits. A reliable review site found that Glad 13 gal. bags hold up to 60 lb of cat litter (think sand if you don't have cats). Another retail site listed these simplehuman bags as holding up to 80 lb. In my testing, they can both handle 30 lb. A no-name brand tore at around 30 lb. I'll try to test their limits.
Whether these are worth the money depends on your budget and your type of trash. If you have light, bulky trash that isn't particularly sharp, then these bags are probably not worth it unless your budget lets you pay twice as much to save a few minutes a month.
If you have dense, heavy trash (such as cat litter), these bags can provide much better value assuming they can really hold 80 lb. You'd need to triple up cheap trash bags to hold 80 lb, and you'd end up paying more since, combined, the three cheap bags cost more than one of these simplehuman bags. Glad bags are roughly on par with these in terms of cost efficiency, but the extra convenience tips the scales in simplehuman's favor for me.
Edit: Did some more testing. These bags can hold 50 lb of weight lifting plates without any apparent issues. 60 lb of plates cause the bags to stretch in the middle after taking a few steps. They would probably fall apart a few seconds after that. Cat litter is somewhat different. It's more spread out, and these bags can hold 60 lb of cat litter without issues, at least for a short walk.
It is definitively worth it to buy the custom-fit-fit bags my Simple Human motion-opening kitchen trash can. The bags are ideal. I buy them by the case. They fit perfectly and each pack stores right on the back of the can. Everyone loves that Simple Human trash can, especially me. The custom-fit bags are an added bonus.
I find this product extremely easy to use and the most durable can liner ever used. We purchased our Simply Human Trash Can in 2017 and have NEVER had an issue with the bags or receptacle. This is truly a Great Product.