Features: 【Double-Window Design】Effortlessly view contents without frequent opening. 【Privacy Pattern Protection】Inner privacy pattern effectively blocks light transmission, safeguarding confidential information from prying eyes. 【Friendly & Safe】From naturally safe silicone, meets environmental standards, and ensures user safety. 【Premium Paper】Durable and tear-resistant, guaranteeing intact delivery. Resists damage or deformation for secure long-distance postage. 【Standard Size Compatibility】Accommodates multiple letter formats, enhancing office efficiency and meeting diverse document mailing requirements. Specifications: Component：Silicone Size: small 22.1x31.9cm/8.7x12.5in 32.2x41.9cm/12.67x4.37in Color: Transparent silicone, with good elasticity and tear resistance. Practicality: Suitable for craft makers Package Includes: 1PC Butterfly Bookshelf Mold Combination note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution