Here in the UK there are several brands available, but the ones we use are made by Lakeland and are available either via the internet or from any of their many high street shops. As you can see here the Lakeland ones are officially called "stayfresh longer" bags.
The science of the bags is explained on the back of the packs:
The bags come in a range of sizes, but the ones we find most useful are the Medium (10" x 15") and Large (11" x 18").
|Medium size. Price: £5.55 for 20|
The large ones are particularly useful for long vegetables like Leeks, Celery and Runner Beans.
|Large size. Price £6.55 for 20|
It doesn't say on the packs how long these bags are supposed to last, or if multiple uses are recommended, but for what it's worth we wash them and re-use them several times and they still seem to perform well. Even when the preservative "Japanese stone powder" eventually fades, their durable plastic composition makes these bags ideal for storing vegetables and fruit. If nothing else, they help prevent soil etc from your veg contaminating the fridge!
By the way, the brightly-coloured plastic clip fasteners, called "Clippits" are also available from Lakeland.
Here we are - some bags in actual use...
This post is not a sponsored one. I just happen to think these are good products. We find that fruit and vegetables stored in them lasts about twice as long as it otherwise would.