Sturdy and Durable? Heat-treated Chrome Vanadium alloy steel mandrels make the Rivnut tools more durable than carbon-steel rivet gun sets. The six sizes of mandrels in the tool kits can meet the needs of various jobs. Easy Riveting? Unique design and thoughtful instruction Manual allows for easy changing of mandrels of rivet nut gun kit by Hand. Wide Applications? The riveters tool-set with ergonomic handles maximizing leverage and for easy operation, saves energy. Delicate Shape Heavy Duty Nut rivet tool is Ideal for Working in Hard-to-reach Areas. Great for Vehicle modifications/Furniture/Metal/Iron/plastic/plate riveting.