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Message: <blockquote data-quote="mayoayo" data-source="post: 3309311" data-attributes="member: 16781">The inner tube has a channel running most its lenght..that helicoidal channel guides the barlow up and down when the eyepiece is turned ,pretty much in the same way that screw in-out eyecups do,,turning right goes up,turning left goes down..the channeled portion of the inner tube offers less friction (less surface),thus allowing the outer sleeve to go in with less work..once the channel ends,the grip increases...That sleeve ,by the way,is not merely cosmetic..it does protect the channel ,so no dust or debris goes inside the eyepiece,and also keeps the prisoner  screw that runs inside the channel,perfectly in place180 pounds ONLY...? No,it would not be the end of the world if it breaks,just the end of the joy you are now seemengly experimenting with Your combo..A win win situation ,for me,implies keeping it working..</blockquote>