This tracing wheel is handy for adding consistent seam allowances to self drafted patterns or when using commercial sewing patterns that do not include seam allowances (such as the Burda magazine) When transferring markings to fabric, use it with tracing paper for better visuals.  The wheels have blunted tips so your pattern paper is not pierced.  The space between the wheels is adjustable in 1/4″ or 0.64cm  increments.