Heavy non powered tool, sits on floor stand, looks to be an adjustable arm. Zebest brand from the early 1990s, may have something to do with bike chains : r/whatisthisthing
アウトドア・スポーツ用品 - テニス、ラケットスポーツ - 個人輸入代行・ebay代行 - BIDBUY JAPAN
Tennis Rare Zebest Sniper High Modulus Oversize Tennis Racquet W Bag Carry Case | eBay
35+ Vintage Tennis Racket Collection - Most Wooden for Sale in Norcross, GA - OfferUp
ZEBRA, ZIBRA, ZEBEST transformation and SNAKY 1 wave shaft 80's model | Talk Tennis