Is your #6 3/4 Remittance Envelopes the same as kost-kut envelopes?
Yes they are. Remittance envelopes, are also known as donation envelopes, offering envelopes and kost-kut envelopes. Remittance envelopes come both as #6 3/4 size and #9 size
6 3/4 Remittance: 3.625" x 6.5" when folded, and 7.25" x 6.5" when flat
9 Remittance: 3.875" x 8.875" when folded, and 7.75" x 8.875" when flat