This traditional yubinuki leather palm or coin thimble from Olympus Thread Mfg. Co. is ideal for sashiko or boro stitching.  You wear it on the middle finger of your stitching hand, with the tab against your palm, and rest the eye of the longer sashiko needles against it to push through several layers of cloth.  Useful for stitching sashiko on tougher fabrics like denim jeans or for sewing through many layers of fabric in boro rag patchwork pieces. The leather is tied with a piece of elastic to hold the thimble securely in place and make it adjustable for all sizes.