Mine is gross and dusty and mismatched because it's been in use for 15 years but it's just ordinary C5 (European size) envelopes! If I can find ones that open on the short edge (probably better known as the top edge in this context), I grab a bunch but I almost never can so most of the ones I have are open to the back side 💔
Thank you @Sandra. That should be C4, right? I sometimes get mail in envelopes about that size, they almost all have the opening on the short side. So maybe that's easier in germany. Most of them are brown though.
Mine is gross and dusty and mismatched because it's been in use for 15 years but it's just ordinary C5 (European size) envelopes! If I can find ones that open on the short edge (probably better known as the top edge in this context), I grab a bunch but I almost never can so most of the ones I have are open to the back side 💔