1. Tesselle Blocks Decorative Cement Breeze Blocks, often called Screen Blocks or Ventilation Blocks, are available from Tesselle in dozens of patterns, and 8 colors. They are ideal for separating and defining spaces, while providing sun protection, increasing privacy, and maintaining openness and airflow. Tesselle carries several patterns in stock, available on a first-come basis, and offers free shipping within the 48 contiguous states. Custom orders are delivered in approximately 12 weeks.