It's just a bit early yet for raspberries here. You can see them starting to form on the plants, but mine won't be ripe yet for another week or two. I did have a bunch of raspberries left from last year in the freezer, which desperately needed to be used. I put the frozen blocks of berries in a large saucepan, with just a little water, set it on the stove and turned it on very low. A while later, the fruit was defrosting and the juice was starting to be released from the mushy raspberries. I had looked for a period 19th century raspberry jelly recipe, but they seem to all require currants, which were not ripe yet. After a bit of research which suggested raspberries are fairly low in pectin, I used a commercial pectin and the packet recipe. I always use the liquid pectin if I'm using it, as it seems to set up better than the dry crystal stuff.
I've read about these but never found them locally. I didn't want to mail order these from the U.S., just for an experiment. But, here they were, right in front of me at the store. They were expensive. The rings which hold the lids down are re-useable and until they get rusty, they don't need to be replaced. The metal lids though, need to be replaced every year. The ones I just bought before I found these, cost $2.88 for a dozen. These plastic lids with rubber rings cost $9.99. That is pretty steep for a product which seems to have mixed reviews, and a fair learning curve to get to work properly. However, the re-useable nature of the item and the advertised BPA free made me want to try them. I used two of the lids on the larger jars, since those are the ones I can guarantee I'll keep for home use. The small jars may or may not end up as gifts, but I didn't want to give away the expensive experimental lids, just in case.
I had no issues getting the two lids to seal. It will take over 3 years for them to start paying for themselves though and by then I imagine I'd have to start replacing the rubber rings. So for a preparedness aspect (you know, for when the zombies eat the electrical grid and nobody makes metal canning lids anymore) and the less product in the landfill, they are an enticing product. For the immediate financial outlay, I'm not so sure. Plus living where we do, I may never be able to find them again, or replacement parts in the future, which would make them very expensive.
Will I use them? Yes, sometimes but until I know that I can purchase them regularly locally, it will have to be the very once in a while extravagant purchase. Besides, they are hard to label. I can't just write on them with a Sharpie, like I do the metal lids... and they're a tad on the ugly side, but that may just be because I am not used to the look yet. You know though, if a case fell off a truck and landed at my feet, I'd use them for sure because the possibilities for environmental benefits would work for me, even if the economics don't.