I had a shock absorber just for the gym from last year, forgot about it, bought 2 new m&s sports bras for after my op then found the shock absorber in my drawer. I’ve worn it all day today cos my other 2 were in the wash and my backs been killing me this evening, I’m sure it’s the shock absorber. Gonna stick to the m&s ones from now on. I got a pack of 2 in a box, 1 black and 1 white for 20 odd quid, they’re not zip up though just normal but they’re really comfy.