mostly cotton, cool in heat ,fits well , good purchase!Well made and mostly comfortable, but for my 38B size, there's too much fabric at the upper cup edge so that the bra doesn't hug the body but gaps out, adding the look of extra inches to the upper torso. The manufacturer could correct this with the addition of elastic along the upper cup outer edges.Not much side support and only 2 hooks. Doesn't seem super sturdy. However, it has a nice cotton feel. Seems like it would be pretty breathable.Everything about about it is great, best bra I have bought in a long time!I was looking for a cotton bra and this bra was listed as 90% cotton and 10% polyamide. When it arrived, I read that it is 80 % polyamide, 15% cotton and 5% elastin. I would never bought it if I new what a real fabric is. Also it running smaller than expected in cup size, I wear 34 DD and bought 34 DDD and it is not a perfect fit, still a little smaller than needed. Very disappointed!Update: after posting my review, I got an email from seller offering me a refund without bothering me sending this bra back. I answered that it will be very nice to get my money back and I will update my review and mention their refund. They’ve never sent me any refund and never communicated to me after that. I just through it out because the band is too big and cups too small and it is almost all synthetic.The bra is made of cotton on the outside , lining is synthetic fabric.I'm allergic to synthetic , what's the use of making a bra of cotton if the fabric which touches the skin is systemic.I should have returned it.It's billed as a sleep bra, but it is adequate for daytime use. The fabric is soft, the cups are plentiful, and and seams provide support without bulk.This product is true to size. I ordered my usual size and it does fit.You cannot wear it under a knot too because seams will show.Ok. We all kinda grow up and tolerate or get used to the fact that the largest joy in life is taking off your bra at the end of the day. This little lovely, however is soooooo comfortable. No pinching. No digging in. It is truly a bra you can put on and forget about. Lovely soft, breathable cotton with super comfy generously padded shoulders. Now for us bigger girls straps are our nemesis but with these straps the pain and pinching is none existant. An amazing little find. AwesomeSuper comfortable, but make your boobs look weird. Probably fine for wearing a baggy sweater.I'm used to regular t shirt bras, and I don't do cleavage or anything exciting so I thought this one was fine.. but boy does this one make my boobs look sad ?All in all if I don't wear anything too shapely around my boobs it's okay.Let's call it a sweater weather bra.And we all know every day is sweater weather if you got body issues ??*Edit* I work from home a lot and now it's my favourite bra. Letting the girls chill out while looking slightly unflattering but who cares when you're this comfortable.Wow oh wow. This is the first time I have bought a bra that fits, comfortably, and at a reasonable price!! During this very hot weather I've had to wear very old, dilapidated bras to keep me sane. I put this bra on and oh the relief. Will buy more if they get them in in my size and other colours. Brilliant product :-)I am allergic to Elastane, it is very difficult to buy bras with less than 5% Elastane but in this one it is minimal . I have worn it for a whole week without a single itch so will be buying some more. The broad straps also make it more comfortable for us bigger girls.Good fit generally, although back size is generous. Really comfortable. I was a bit disappointed at first because the area under the cup is more padded and synthetic (to offer more support I guess), but it's actually very cool and easy to wear, even in the hot weather. Think the price has hiked up, not sure if I'd be so keen to buy again, but it is a good product, and you can't cut corners with good underwear!