Check the listing for details. - Blocking Mats for Knitting & Crochet Projects, 12" X 12", 9 Pack with 150 Pcs. Condition: New. Listed at 38.59 USD. This set includes 150 T-pins, which are perfect for blocking projects, ensuring your creations maintain their shape and structure during the drying process. Made from high-density, heat-resistant, and water-resistant material, these mats are designed to withstand frequent use while maintaining their durability and shape.