This is a black TYR Durafast Elite or Durafast One Maxfit swimsuit.

This appears to be a TYR Women's Maxfit or Diamondfit solid black performance swimsuit. These styles feature a keyhole back and moderate-cut leg, ideal for training or competitive swimming. Key Features Brand: TYR (pronounced "tier"), an American manufacturer of competitive swimwear. Material: It is likely made from TYR's Durafast Elite or Durafast One fabric, a blend of polyester and spandex that is 100% chlorine-proof and designed to last over 300 hours of use. Coverage: The suit offers fuller coverage with a medium neckline, thick/supportive straps, a keyhole back, and a moderate cut leg, providing reliable support without weighing you down. Availability: These swimsuits are available at various online retailers and sporting goods stores, with prices generally ranging from £20 to £54, depending on the exact model and retailer.