I use a "GXMmat Extra Large Exercise Mat," which is 6 feet x 8 feet in size. I use it on the wood floor of my second-floor apartment 4 or 5 days a week. It won't completely deaden the noise below, but it's pretty thick (7mm), and I can place a kettlebell on it without making a racket. At the end of each use I take a minute to roll up the mat and lean it upright in a corner. The extra large size is perfect for sprawling out with TGUs and other floor exercises. I'm sure the next size down would also be fine if you're tight on space. https://www.amazon.com/gp/product/B07GTLYJ4L/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1