A:Answer The remote you're looking for that comes with BestBuy's 3811X, the one with a 3.5mm headphone jack, is a Model# RC-AL8 / Part# 3226000703.
This remote is exclusive to the 3811X and for some reason BestBuy does NOT sell it separately. Roku offers the RC-AL9 on their website (when they have it in stock), but it's half the price of the 3811X. Most people needing to replace the remote, if it's not damaged, buy a new 3811X and swap out the remote, returning the 3811X as defective. It's not the most honest way of replacement, but until BestBuy steps up and exclusively offers the RC-AL8, there's few options.