Quality Park® Window Envelopes are essential for your business. The reflex blue pattern protects sensitive client information because it's impossible to see the details of the contents, even when held up to light. These 24-lb wove envelopes have traditional diagonal seams compatible with automated inserting and folding equipment. Each business envelope has a moisture seal commercial flap. Stock up on boxes so you don't run out!. Security Tint. Seam Type: Diagonal; Flap Type: Commercial; Trade Size: #10; Security Tinted: Yes.