CertainTeed 
CertainTeed’s Siding Products Group (SPG) is the leading manufacturer of vinyl siding and polymer shakes and shingles. It is also a major producer of cellular pvc exterior trim and vinyl fence, railing and deck. SPG products are manufactured in seven plants in the U.S. and sold throughout the U.S and Canada.
Plycem USA
Advanced technology in fiber cement. Plycem’s fiber cement trim is reversible, weather resistant, and environmentally friendly – an affordable alternative to other exterior trim products. With the broadest line of fiber cement trim available and more than 20 years of proven performance, Plycem has all the advantages of wood trim without the limitations.
SAF - Perimeter Systems 
Perimeter Systems – a division of SAF. Since 1990, Perimeter Systems has provided Designer Series Cornice Mouldings & Trims for churches, universities, financial institutions, and municipalities throughout the United States. Whether new construction or historic renovation, our innovative "interchangeable" mouldings allow you to design beautifully sculptured cornices and trims in both formed or extruded aluminum profiles.
Versatex 
At Versatex Trimboard we make trim smarter. Our products are created from cellular PVC for trim, fascia, soffit, or decorative exterior moulding pieces. Our products include trimboards, sheet, cornerboards, T&G beaded profiles as well as our innovative patent-pending Stealth Trim System, all manufactured with the highest level of quality and featuring a fully transferable 30-year limited warranty.
4specs Discussion Forum - Great place to ask questions about specifications, products and technical data. Free - no registration required to read or post (subject to moderation).
See also: 06 4500 - Standing and Running Trims (for standard wood trims)
CertainTeed
CertainTeed’s Siding Products Group (SPG) is the leading manufacturer of vinyl siding and polymer shakes and shingles. It is also a major producer of cellular pvc exterior trim and vinyl fence, railing and deck. SPG products are manufactured in seven plants in the U.S. and sold throughout the U.S and Canada.
Plycem USA
Advanced technology in fiber cement. Plycem’s fiber cement trim is reversible, weather resistant, and environmentally friendly – an affordable alternative to other exterior trim products. With the broadest line of fiber cement trim available and more than 20 years of proven performance, Plycem has all the advantages of wood trim without the limitations.
SAF - Perimeter Systems
Perimeter Systems – a division of SAF. Since 1990, Perimeter Systems has provided Designer Series Cornice Mouldings & Trims for churches, universities, financial institutions, and municipalities throughout the United States. Whether new construction or historic renovation, our innovative "interchangeable" mouldings allow you to design beautifully sculptured cornices and trims in both formed or extruded aluminum profiles.
Versatex
At Versatex Trimboard we make trim smarter. Our products are created from cellular PVC for trim, fascia, soffit, or decorative exterior moulding pieces. Our products include trimboards, sheet, cornerboards, T&G beaded profiles as well as our innovative patent-pending Stealth Trim System, all manufactured with the highest level of quality and featuring a fully transferable 30-year limited warranty.