Coin Slabs Or Snaps With White Inserts?

Since Coin World Premier stopped making slabs with white inserts I'm having trouble finding a suitable replacement.

BCW makes some but they are in limited sizes (common US coins).

I collect Canadian colonials, sizes are all over the place, and I prefer white inserts for heavily toned coppers (coins seem to pop much better than with a dark insert)

Does anyone have any suggestions?

I've found generics on ebay and also PCCB brand but I am nervous about long term storage.

I did do a copper wire burn test on the PCCBs, didn't appear to have the green flame associated with PVC, curious if anyone else has used this brand?

thank you