Classed by Royal Mail as 'Large Letter' size. 200 x Size F (3) Jiffy Airkraft Padded Bubble Envelopes. These are equivalent to mail lite/feather-post size F - the internal measurements of each envelope are 220mm x 320mm.
200 x Jiffy Airkraft Size 3 (F) Padded Envelopes 220x320mm[5055502315478]