It has to be BIAB™ the only builder gel everyone wants. Our darkest BIAB™ shade Slate is an off-black with rich charcoal undertones in our revolutionary builder gel formula. Slate will give your clients stronger and longer nails in a bold and sophisticated finish that will make a statement. Apply. Top. Go! Black BIAB™ nails are something everyone's been asking for and now available in Original BIAB™ for long-lasting results that last up to 5 weeks.