I just watched a video where the goalie (I think trav4oilers?) said his goaliecoach recommended these bmx kneepads under his goalie knee pads to absorb extra shock.

As others pointed out, this is to soften the landing and to be used with knee pads

You can get some bmx knee pads that do the same thing, but are way cheaper. I wear them with other compression pants. It's nice to be able to swap out pants between games.

here's an Amazon link, Black Logo, Adult Large https://www.amazon.com/dp/B07JJ27PVP/ref=cm_sw_r_apan_i_G5ZWER3ADTAJEW04QTC5?_encoding=UTF8&psc=1)