With thinner walls than Schedule 40 fittings, these are lighter in weight and have more space on the inside for high-flow applications, such as underground gravity-flow sewer and storm drainage lines. They are also known as SDR 35 fittings.

Fittings are polished to a32 Ra and under finish on the interior.

Polished to at least a 15 Ra finish on the inside, these fittings have an ultra-smooth interior surface that helps prevent contamination. They are also known as ultra-high-purity fittings.