I'm selling this because I don't use it much at home. I place this mat from my tailbone to my back during crunches. It stimulates the abdominal muscles in just the right places. Below is the product information from the online product page for reference. https://fitcraft.stores.jp/items/61de59f947a5345f7e825ee0 It fits the natural curve of the spine and enhances the effectiveness of abdominal training! The flat side on the back has a non-slip surface! ◯ Product Name: Reebok Ab Wedge Mat ◯ Product Number: RSMT-40010 ◯ Dimensions (Length x Width x Height): 30.5 x 36 x 7 cm ◯ Weight: 600 g ◯ Market Price: 5,720 yen Thank you.