Are these microwave absorbers any good?

[grg183]

I'm looking for affordable microwave absorbers for minimizing reflections during measurements. I don't need many and not necessarily top-of-the-line quality, I need just a few for strategical placement. I've noticed several vendors on Alibaba offering low-cost pyramidal microwave absorber tiles, like this one: https://www.alibaba.com/product-detail/Pyramidal-Microwave-Absorbing-Foam-rf-Absorber_1600306531990.html 

Given the low-cost I'm quite skeptical of the real specifications of these absorber. Has anyone used these (or from similar vendors) and can share their experience?

[CaptDon]

Can't tell you if that exact product is any good, but the design is the standard of the industry for E.M.I. test chambers and the ones that have about a 2Ft. square footprint usually run a couple hundred U.S.D. I guess they do share the same fancy blue color with the cheap knock-off stuff. The good absorbers are a conductive foam similar in nature to the foam that CMOS I.C.'s used to be stored on. One company called them 'bug rugs'. Like all foam your multi-thousand dollar investment will crumble and disintegrate over time!! I have brushed so much of that stuff out of my hair when setting up tests in an old lab about 20 miles from my home. Several of the 'blocks' have fallen off the ceiling lately.

[coppercone2]

you know I wonder if that room is bad for you, they found a issue with CPAP machine foam giving people lung problems.