Here is the Sweetwater product page for a "Generic Viola Chin Rest Barrel - 35mm", used to clamp the chinrest (or an electric pickup, in my case) onto an instrument:
The URL says "generic-viola-chin-rest-barrels-35mm", and until yesterday, the product page used the term "Barrels" in the title and "pair of chinrest barrels" in the description.
This discrepancy is because of me! I ordered one (1) of these items a week ago, believing that it would be a pair of barrels, and received only one. I contacted support explaining what happened, they very promptly shipped me the missing piece today, and now... for a moment I thought I was losing my mind because they've rewritten the page to remove all references to "Barrels" or "pairs"!
Love to be, presumably, the first and only person who gets to take advantage of this particular thing and thus save $4