Our W-2 4UP envelopes have two windows, and are compatible with our W-2 forms. They are moisture seal envelopes, and have a tint inside that provides security through delivery.
Overall size: 8 3/4" X 5 3/4"
Top Window: 3 7/8" x 9/16"
Position: 5/16" from left, 3 9/16" from bottom
Bottom Window: 3 7/8" x 11/16"
Position: 4 3/8" from left, 2 1/2" from bottom