Fiberglass Cracked Bathtub Floor Permanent Repair Inlay Kits. Permanent repair for cracked fiberglass plastic and acrylic bathtub floors. Inlay measure 16 x 36 and comes in bone or white colors. Easy Bathtub Floor Repair Inlay Kit to install in less than an hour and repairs last the life of your bathtub. Non slip surface and may be refinished in any color to match your bathtub. Free shipping in 48 United States.