Spring Tensioner: https://www.amazon.com/Witbot-Stainless-Tensioner-Ultimaker2-Printer/dp/B01KHKJ5OO/ref=sr_1_2?dchild=1&keywords=gt2+belt+tensioner&qid=1601504167&sr=8-2

I'm also including a link for a belt, I bought my tronxy years ago and the one that came with mine was a shitty plastic belt, so i upgraded to a rubber, fiberglass reinforced belt. Belt: https://www.amazon.com/Printing-Zeelo-Fiberglass-Rostock-Printers/dp/B08974S1CC/ref=sr_1_1_sspa?dchild=1&keywords=gt2+belt&qid=1601504302&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEySkRaN1I0U0ZCSDhOJmVuY3J5cHRlZElkPUEwMzkwNDUzMTFESFFVU1lYSFJYNCZlbmNyeXB0ZWRBZElkPUEwNjE2NzI0RDJRV0NBSkJGUVlSJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==