6-46mm Open End Wrenches Double Head Spanner Wrench Spanners Metric Carbon Steel

Measure the distance across the flats of the bolt head or nut with a caliper or ruler — that measurement in millimeters is the wrench size you need. Each wrench in this range covers two adjacent sizes (for example, 10–12 mm), so one tool handles both fastener dimensions. If you are unsure, select the next size up and work down until the jaw fits snugly without play.

Carbon steel open end wrenches are suitable for general automotive maintenance tasks such as tightening bracket bolts, adjusting suspension components, and working on engine accessories. For high-torque applications such as wheel lug nuts or crankshaft bolts, a torque wrench or breaker bar with a socket is the more appropriate tool. Always apply force in a controlled manner to avoid rounding fastener flats.

The corrosion-resistant surface treatment provides meaningful protection against light moisture exposure — typical of a garage or outdoor shed. For long-term storage in high-humidity or salt-air environments, wiping the wrench with a light machine oil after use will extend the finish life and prevent surface oxidation.

These wrenches are sized in metric millimeters and are designed for metric fasteners. While a metric jaw may physically fit over a similarly sized SAE fastener, the fit will not be precise and risks rounding the fastener flats. For SAE fasteners, use a wrench set sized in fractional inches.

The 1 Pcs option ships a single wrench in your chosen size. The 2 Pcs option ships two identical wrenches — useful if you want a spare for a second toolbox, need to lend one to a co-worker, or are stocking a shared workshop where tools frequently walk away. Pricing per piece is reflected in the variant price shown on the product page.

An open-end wrench can be used on flare nuts when a dedicated flare nut (crow's foot) wrench is not available, since the open jaw can be positioned over the tubing. However, for critical brake and fuel line work, a proper flare nut wrench that wraps more of the nut's perimeter is recommended to reduce the risk of rounding the soft brass or steel fitting.

Check the fastener markings on the bolt head (metric bolts often stamp the size or grade on the head), or use a digital caliper to measure across the flats. The variant selector on this page lists all available size ranges — choose the range that includes your measured fastener size. If you need help confirming compatibility, contact us before ordering.