But, i prefer Sandisk flash memory vault which can store data up to for 100 years
Other option is Ledger Wallet, Hardware USB wallet for store your bitcoin
Yes! This was actually the first one I had in mind. Surprised to see I'm not the only one who knows about this. It's really designed to store photos but there's no reason why you can't store an encrypted BTC wallet in there. Normal flash drives will actually lose some/most of their data after a few decades due to electron leakage so they're not suitable as a very long term cold storage option.
There is one slight caveat though. Since the purpose of the drive is to act as long term storage, you can't replace any files stored inside. So once the drive is completely filled up with data, that's it.
I think he chose 4 GB because that's about the lowest capacity you can find in stores these days. I suppose even a 128 MB drive would be sufficient for something like this.