9.5" x 2.5" x 2.5" approximately
The tailor’s clapper is used to get flat, crisp seams and creases while sewing. The wood itself absorbs the steam, and traps the heat inside of your fabric, instead of setting it free into the air of your sewing room. This is the magic of the tailor’s clapper. Your fabric needs the right combination of hot to cool, steamy to dry in order to make a perfectly flat seam.
Heat and steam make fabric fibers flexible, and when they dry and cool to room temperature they stay in the shape they were when hot. That’s why pressing works in the first place! But when you’re just pressing, you remove the pressure of your iron while the fabric is still hot, so the fibers can relax out of shape before they cool and stiffen.
So a tailor’s clapper keeps the heat and steam trapped for an extended period of time, which gives the fibers more time to get into the desired shape - meaning perfectly flat - and then holds them in that exact shape while they cool.