Synthetics, nice. Suitable for 75A/b/s, I have an OPG 77, OG 90, sat perfectly. Went for a long time, the seams are even, the fabric is in the hem, the threads do not stick out, there is no smell, the straps are wide. On the sport will go, keeps well enough. A little push-up, the cups are pulled out. Recommend! Still, it will not go to everyday, synthetics. On sports or not long to wear-good