They keep for 12 months or more, they do catch fish but they are not a magic bait. Somedays they want red, some days green, somedays you cannot buy a bite on them!!
I think they are better when temperatures are rising, late spring for example, and when they are falling Sept/Oct for example. I struggled on them when it was hot in August.
Now I only use the 6mm ones whereas earlier this year the 10mm were better.
Lots on here slag them off. My advice is to probably give them a miss if the price tag is too high for you as they are not, as I have said above magic.
One final observation, they seem to work better on some venues than others, I have no idea why.

There is a debate that continues on these.
We sell them on our web site, so I have an affiliation with them, however I can say that it was using these that gave me the idea set up the web site.

To put some balance on the matter, there are days where I cannot buy a bite on any of them. However when nothing else is working, I put one on and an immediately have a fish on. Other days I use them all day and bag up.

There is no catch all bait to use on all occasions, but many many customers of ours use them time and again.

all i can say about them is ive used the red 6mm in winter league matches hair rigged on the bomb when ive really struggled for a bonus fish and the tip has never failed to go round so theres allways a jar in my bag so for me they are a confident thing perhaps not for others

They do catch you fish but I would not describe them as a bagging bait. Work very well in cold water, this weekend a good example. Caught me fish when no other bait did. Also good on the tip in winter. Just finishing my first jar and will definitely buy another, have only tried the red. Worth the extra money for the extra fish.

Keeping them on the hair is not easy. The bait spikes are not foolproof and the band pulled through isnt either. I am ok on the 10mm but has anyone found a sound method for the 6mm hair rigged on the bomb?

i fished a match at woodlands view yesterday, he allows own hook pellets now but no jpz’s, according to the rules, must be something in them??

May seem expensive but a jar has lasted me all my club matches this season (10 matches) As to do they work? Yup! Fished on after a match I had won in september as the carp were just turning up in the margins, about 6 of the lads stayed and watched. A few saw the jpz’s on my tray and said they would never pay that much for some hook pellets! So I said ok watch this, put a grain of corn on (feeding hemp and corn) float settled and wobbled a bit, worked it a few times and eventually got a bite after about 4/5 mins. Fed again and put a jpz on float settled and shot under instantly, did this about four times sometimes not getting a bite on corn (sometimes carp ripping elastic out on jpz) before they all said “my word” (or something like that!) and asked me where they could get some.

never used them, are there mainly a bomb bait or can you use them on the pole?