| Prior to placing your order, you must determine the size and style of the mast groove (width "A" and lip thickness "B"), or width of existing external track "F". Ultra Marine will send you a set of measurement discs which were developed for this purpose (see below). |
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Each disc has a series of gauged studs which correspond to the most common mast groove configurations. The discs with numbered studs are for determining slot lip thickness. Lettered discs are for determining slot width. |