Polypropylene—The body of these clamps stand up to water, most acids, alcohols, and salts. They’re commonly used to route tubing in food processing, lab, and outdoor installations.

Aluminum—Best for extreme conditions, these clamps can handle temperatures up to 570°F. They won’t rust when exposed to salt water or mild chemicals, but they shouldn’t be used with stainless steel to avoid contact corrosion. Although stronger than plastic, they’re four to five times heavier and not suitable for weight-sensitive applications.

Steel Top and Bottom Plate—Best for dry environments since moisture will cause these plates to rust.

Zinc-Plated Steel Top Plate and Zinc-Phosphate-Coated Steel Bottom Plate—With a layer of zinc to protect against corrosion, these plates are a good choice for areas with occasional exposure to moisture. The layer on the bottom plates is thinner than the top plates, making it easier to remove before welding.

304 Stainless Steel Top and Bottom Plate—These plates are suitable for a wide range of corrosive environments. They won't rust in wet areas and hold up against mild chemicals and solvents.