Wood A-Frame Chalkboard Sidewalk Sign for Wet Erase and Traditional Stick Chalk, 21" x 34" Boards Slide Out for Easy Updating Double-sided enables advertising from multiple directions. Designed for outdoor use only in fair weather conditions. Not suitable for windy or wet weather. Two, slide-in 21 x 34 -inch boards allows you to design messages prior to them being displayed. Folds flat for easy transportation and storage. Use with traditional stick chalk, liquid chalk and wet-erase neon pens.