OEM Quality Park Redi-Seal 2 Window Envelopes come in a box of 500, designed for easy and efficient mailing. These double-window No. 9 envelopes feature a Redi-Seal Closure that does not require moisture to seal, ensuring a hassle-free experience. The unique double-flap design prevents the gum from sticking before use; simply raise the lower flap and press to seal. Made from 24 lb. white wove paper with poly windows and inside tint for added security.