A sailmaking palm allows you to put extra strength and tension onto the twine in hand sewing applications, so it’s a must-have for thick assemblies. Although these accessories are designed for sailmaking and canvaswork, they are also useful for a variety of other heavy-duty sewing applications where you’re working with thick materials such as leather. A durable thumb shield protects the thumb when roping, as the twine is wrapped and then pulled hard over the thumb while in use. For left hand.