No. 10 colored envelopes are perfect for your mail, classroom notes or any correspondence in need of a special pop of color. From the classroom to your craft room, these envelopes are the perfect way to brighten someone's day and make sure notes from home don't get lost in the shuffle of a backpack or regular mail. 24 lb. envelopes ensure easy printing with a distinctive look. Acid-free, lignin-free construction lets you display and store your creations with confidence without yellowing over time.