Question about these stock sheets

Hi Anil,
do we have any packaging that came with these?
Where did the page come from?
Any reference as to what they are, and what they are for?

Apart from the backing, the clear plastic looks dodgy.

I have seen in the past, stamps saved in clear plastic Coin Pockets, and the stamp ink had leached into the plastic.
Be careful.

Did the ad mention the plastic used? They look flimsy.

Anil, I agree with your thought about returning them and recommend that you stick with the well-established brands (e.g., Vario, Hagner, etc.). If you're just storing inexpensive duplicates you might consider manila stock sheets as a less costly alternative.

Thank you,
I think you have made the better choice.

The second advert........... and I quote

About this item

PROFESSIONAL STAMP POCKET - Each pack of 12 sheets with 24 pages, 4 mixed sizes and 3 sheets of each size, suitable for stamps with height under 50MM
PREMIUM MATERIAL – Eco-friendly PVC sheets and PET pockets, durable and free of acids and chemical softeners that will not cause any damage to your stamp collection

TRANSPARENT POCKET - Double-sided insertable high transparent thick pages, convenient for you to collect, view, display and exchange your stamps
SUPERB CRAFTSMANSHIP - The black page is one-piece hot-pressed and has no traces of splicing, so that it will not be easily torn. This 9-hole loose leaf is suitable for most stamp album clips
WIDE USAGES - Convenient to store and display various sizes of stamps, banknotes, invoices or other collectibles. It is also an excellent gift for friends, family, and collectors
They look similar to Vario, but PVC ?  Poly Vinyl Chloride ? I don't recall that being safe,  PET pockets?

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  australiapostcollectables.com.au/articles/stamp-collecting-tips-for-beginners-part-2#:~:text=Remember%2C%20whichever%20route%20you%20take,damage%20to%20paper%2Dbased%20materials.

Remember, whichever route you take, protective enclosures should be composed of archival quality, acid-free materials in order to prevent the transfer of acids and other chemicals to your stamps. Plastics containing plasticisers (PVC) should be avoided, as they can cause serious damage to paper-based materials. Polypropylene, polyethylene and polyester have different properties, but they are all chemically stable and can be used for storage purposes. Always read the label or check with your supplier to ensure that the product you are buying will not introduce harmful acids and chemicals into your collection. The collection should be kept clean and regular inspection is important.