Product review (4 stars): nearly 11x13. took a chance.
actually needed a replacement carbon/metal filter for a Fasco 383 hood (11x13 non ducted)
it uses 2 inserts - an only-metal one (washable) and a metal+carbon one.

the 11x13 carbon one is surprisingly hard to find, and pricey.

took a chance on these given the description, and had some luck! - fits perfectly.