This is cypress wood about 7-10mm thick. It's slightly thinner to keep the price down. Cypress is very durable and can be used for many years. I also have another listing for a thicker board, closer to the actual thickness of a mailbox slot, which reduces errors from diagonal insertion. The photos are for size and shape reference. The item you receive will be of equivalent quality. This item was created out of necessity by myself, a Mercari user, who thought it would be useful. I'm confident you'll be satisfied. Nearly 1000 people have already enjoyed and appreciated this product. Cypress has a wonderful scent that is very relaxing. Wood is flexible and strong, becoming more refined with use, and is gentle on the environment. Above all, the texture of wood is superb. I've received many comments expressing surprise at how durable and pleasant to the touch the product is. I've been using mine for a long time. Unlike thin rulers, it doesn't bend or flex. It's sturdy, just like a real mailbox slot. You can check beforehand if a package can be crushed and pushed through. I don't believe there are any commercially available slot measurement tools with this level of thickness. If you would like a measurement slit of a different thickness (e.g., 1cm or 5cm), please contact me via the comments on the custom order page. While it may take some time, I will do my best to accommodate your requests. I will use recycled packaging materials. If you purchase multiple items and they can be shipped together, I will offer a discount equivalent to the shipping cost. Please note that I may change between Yu-Yu Mercari便 and Raku-Raku Mercari便 without prior notice. Thank you for your understanding. #TakaWataruHandmade #TakaWataruPackingScale #YuPacketPost4cm #YuPacketPost #ThicknessMeasuringRuler #ThicknessGauge #ThicknessMeasuringItem #ThicknessMeasuringGoods YuPacket Post Thickness Gauge 4cm Thickness Measurement Ruler Scale YuPacket Plus Measuring Ruler Mercari Shipping Mercari Scale Shipping Ruler Thickness Measuring Ruler Thickness Measuring Item Thickness Measuring Goods Thickness Measurement Scale