underlay (Waverton CH3)

10mm UNDERLAY B&G 5 star
Clean but stored in garage for 20 years as leftover after carpet fitting
83" x 52" plus scraps

but the main 83" x 52" piece needs patching with the scraps - there's a 2" hole, some bits on the edge where the rubber has been eroded - alternatively just cut out a 48" x 36" rectangle which is perfect, or you could cut out a larger piece than that and exclude the lowest quality bits. Up to you.

Or cut it up and mount the rectangles on top of each other as a thick rubber mat for exercise purposes or whatever!