Orion 7371 100mm ID Telescope Tube Rings<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"> Set of two 100mm inside diameter cast-aluminum telescope tube rings with quick-release， hinged clamp knobs and felt lining </span></li><li><span class="a-list-item"> One ring has 1/4"-20 piggyback camera adapter; the other tube ring has a threaded 1/4"-20 hole </span></li><li><span class="a-list-item"> Sold in sets of two telescope tube rings with mounting bolts included </span></li><li><span class="a-list-item"> Use with any Orion equatorial or altazimuth telescope mount - use with some mounts may require a tube ring mounting plate (sold separately) </span></li><li><span class="a-list-item"> Inside diameter of each tube ring is 100mm - works with 100mm diameter telescope optical tubes </span></li></ul></div><img src="http://ecx.images-amazon.com/images/I/31MEP67T14L.jpg" noproxy>