Reddit reviews Pole-Wrap 3-1/2 in. Dia Oak Cap and Base Set
We found 1 Reddit comments about Pole-Wrap 3-1/2 in. Dia Oak Cap and Base Set. Here are the top ones, ranked by their Reddit score.
Use this model size for 11 in. circ (or 3-1/2 in. Dia) columns - actual trim hole size is 4 in. Dia to fit over WrapPremium solid red oak for finest appearanceInstalls quick and easy with construction adhesive (e.g., liquid nails - not included)Can be stained or just use polyurethane to bring out natural wood beautyRequires installation of 12 in. oak wrap (sold separately)
without a pic, hard to tell, but i think what you are looking for is a "split-ring escutcheon plate". these are typically used for plumbing, so not sure if they make them in the right diameter for your pole. you need the split ring as i assume you dont have access to the top of the pole to slide a non-split one down the pole, you would need to have a 2 piece one (split-ring) that you assemble around the pole.
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edit: or maybe something like this.