Can be used on both sides. There is a rubber string opening. You can replace it yourself. Width: Approximately 17cm Height: Approximately 9.5cm There may be slight differences in color between the image and the actual product. This is a handmade item by an amateur. There may be some errors, distortions, and misalignments. Thank you for your understanding and consideration. Shipping will be done using recycled materials and simple packaging. Thank you.