Here I have a box of C5 envelopes by Postmaster

C5 ENVELOPE - Designed to take sheets of A4 Paper folded in half, or sheets of A5 paper
unfolded. Designed to be sent using a single 1st Class or 2nd Class Stamp (max 100g)

KEEPS YOUR DOCUMENTS PRIVATE - envelopes are printed on the inside with an opaque grey pattern that makes it difficult to see what is inside the envelope

PEFC-CERTIFIED FOR SUSTAINABILITY - PEFC is a European based Forest certification system, that allows small and family forest owners to demonstrate their excellence in sustainable forest management

HYGIENIC & FAST - this envelope features sticky closure, although this has deteriorated in storage and will need a bit of cellotape to stick firmly, hence the asking price.

MADE IN THE UK

Specification:-

Size: 16.2 x 22.9 x 0.05 cm
Qty: 500
Colour: White
90GSM