Weems &amp; Plath Marine Navigation Bi-Rola Rule (18-Inch)<div style="text-align: left;"><strong>[Product Information]</strong><ul><li id="replacementPartsFitmentBullet" class="aok-hidden" data-doesntfitmessage="We're not sure this item fits your " data-fitsmessage="This fits your "><span class="a-list-item"><span id="replacementPartsFitmentBulletInner"><a href="#" class="a-link-normal hsx-rpp-fitment-focus">Enter your model number</a>to make sure this fits.</span></span></li><li><span class="a-list-item"> Patented four-way rolling motion </span></li><li><span class="a-list-item"> Roller body has protractor markings every 1/2 degree </span></li><li><span class="a-list-item"> 1-1/4" magnifying lens for enhancing chart data </span></li><li><span class="a-list-item"> Easy to follow instructions </span></li><li><span class="a-list-item"> Packaged in a protective， durable vinyl pouch </span></li></ul></div><img src="http://ecx.images-amazon.com/images/I/31Em0d7qg6L.jpg" noproxy>