This is a Box of 500 Vintage DRG Defiance DL Pocket Envelopes 0 2231 4

They are DL Size, 220 x 110mm.

They say seal-easi but I very much doubt that will still work ! You will probably have to put a bit of tape on !

They will have some discolouration due to age.

I think they are  from the 80's.