Long Black Mermaid Sweetheart Beaded Satin Prom Dress with Slit BIZTUNNEL Long Mermaid Sweetheart Velvet Black Formal Prom Dresses with Slit Black Formal Dresses With Slit & Windsor Black Beaded Sweetheart Mermaid Long Prom Dress with Slit Modsele Gorgeous Black Velvet Off The Shoulder Mermaid Prom Dress Split With Long Mermaid Prom Dresses & Windsor. This exquisite prom dress features a black velvet mermaid silhouette with a sweetheart neckline and a slit for a sensational night of dancing. The luxurious velvet material gives it an air of sophistication perfect for any formal occasion.