- Topaz molded fiberglass bathtub 3 piece bathtub walls are easy to install and fits a 60 In. x 30 In. alcove and adapts to most standard 5 Ft. steel or fiberglass bathtubs. Walls fasten direct to studwall and have interlocking panels to form tongue 'n grove connection. Smooth, semi gloss surface is easy to clean and resistant to mold and mildew. Color: White