MAYES 10742 Polystyrene Level Ruler 12", Precision Measuring and Leveling Tool, Plumb and Level Vials with SAE and Center-Finding Scale, for Framing, Hanging, Made in the USA

A compact level-ruler that punches above its weight

I’ve carried a lot of levels and rulers to jobsites and around the house, but I kept reaching for one tool most over the past month: a 12-inch level ruler from Mayes. It’s a simple idea done well—combine a straight, readable SAE scale with reliable plumb and level vials in a slim, lightweight body. For small layout, hanging, and trim tasks where a 2- or 4-foot level feels clumsy, this little green stick is faster, easier to see, and less likely to mark painted surfaces.

Build and design

The body is polystyrene, a high-impact composite that feels tougher than bargain-bin plastic yet remains featherlight. It doesn’t have the rigid heft of an aluminum box level, but it also doesn’t scratch wall paint or tile. The 3/8-inch thickness is genuinely slim; it tucks into a tool bag slot, rides in a kitchen drawer, and sits flat against trim without a wobbly overhang. A hang hole makes storage straightforward.

Color choice matters on a layout tool, and the bright green is more than a style cue—it makes the black inch markings easier to read in middling light. The vials are cleanly set and protected inside the body, not exposed with protruding end caps. This keeps the profile sleek, though you lose the rubber bumpers you’d get on a jobsite level.

A couple of important clarifications:
- This is an SAE-only ruler (inches and fractions), not dual-scale with metric.
- It’s not magnetic. If you need a level to stick to steel studs or door frames, plan accordingly.

Vial accuracy and readability

I check every level against a reference surface (flip test on a straight countertop and a known-flat plate). The Mayes 12-inch level passed those checks easily. The bubble centers consistently in both directions for level and plumb. The vials aren’t oversized, but the contrast is good and the bubble edges are crisp. I had no trouble reading them across a small room or at arm’s length above head height.

Because the body can flex slightly, your technique matters: don’t press the center hard against uneven surfaces. Let the tool bridge the surface with light pressure at the ends. Used that way, I found the readings repeatable and trustworthy for the kind of tasks this size level is meant to handle—picture rails, shelf brackets, door hardware, and tile courses.

The ruler and center-finding scale

Mayes combines a straightforward inch scale with a center-finding layout that turned out to be the star of the show. There’s a zero at midspan with mirrored graduations left and right, so you can:
- Find the midpoint between two edges by matching the same reading on both ends and marking zero.
- Balance hardware placement without doing math, especially handy for frames and cabinet pulls.
- Lay out tile or trim patterns symmetrically from a centerline.

On my sample, the print registration was clean. I compared the graduations against a steel rule and a high-quality tape—markings lined up, and the zero offset at the edge was correct. As with any printed scale on a polymer body, it’s worth giving yours a quick once-over before a precision task: check the first inch against a known reference and confirm the zero/edge alignment.

In use: where this tool excels

• Hanging art and shelves: The center-finding scale is fast. Place the tool, align equal readings, mark the zero. Then flip the level function on and you’re drilling confidently.
• Tile layout and trim: For short runs, backsplashes, or setting that first course, it’s nimble. I used it to strike reference lines on tile backer and to verify level at niche edges.
• Cabinet and hardware install: The small size fits inside boxes and against stile edges. It’s ideal for knobs and pulls where a long level is awkward.
• General layout: Marking cut lines on sheet goods, finding centers on boards, or transferring marks—its non-marring body plays nicely on finished surfaces.

The lightweight build means I actually keep it on me, which is half the battle. A tool you carry beats a more “pro” tool left in the truck.

Limitations to keep in mind

• Flex vs. rigidity: Polystyrene has a bit of give. For longer spans or uneven surfaces, a rigid aluminum level will bridge dips and humps better. With this one, apply light, even pressure or use a known-straight edge beneath it for critical readings.
• Short length: Twelve inches is perfect for tight spots, not for leveling long countertops, ledger boards, or door jambs. It’s a complement, not a replacement for a 24–48 inch level.
• No magnets: If you work on steel studs or appliances, you’ll miss magnetic hold.
• SAE only: If metric is part of your workflow, you’ll need another scale or a different model.

Durability and maintenance

I’ve knocked it off a step and tossed it in with hand tools—no cracks, no lifted vials, no smeared markings so far. That said, it’s still a composite body. I wouldn’t expect it to shrug off the sort of abuse a box-beam level can take. If you cut, scrape, or melt polystyrene with solvents, the finish will suffer. Basic care tips:
- Avoid strong solvents or paint thinners on the printed scale.
- Store flat or hanging to keep the body from taking a set under weight.
- Wipe off grit before readings so debris doesn’t lift the edges and skew the bubble.

Practical accuracy checks you can do in a minute

• Level flip test: Place it on a flat surface and note the bubble. Flip end-for-end; the bubble should read the same. Repeat for plumb against a door jamb.
• Scale check: Lay a known steel rule or good tape alongside; verify the first inch and a few random marks. Confirm the edge-to-zero relationship if you rely on edge starts.

These quick checks are good practice for any compact level-ruler, not just this one.

Who will appreciate it

• DIYers and homeowners who hang things regularly and want speed without wall scuffs.
• Finish carpenters and installers who need a small, accurate reference in tight spaces.
• Tile setters and painters who benefit from clean, visible layout marks on finished surfaces.
• Anyone who values the center-finding feature for balanced installations.

If your work is framing or structural layout, this is a secondary tool. For finish work and household projects, it’s often the primary one you’ll grab.

Alternatives and pairings

• Pair it with a 24–48 inch rigid level for longer spans.
• Add a chalk line or laser for room-scale layout; use the Mayes as a quick verifier and for marking measurements the laser can’t.
• If you need metric markings or magnets, look at a different variant or an aluminum alternative.

The bottom line

The Mayes 12-inch level ruler is a thoughtfully executed, everyday tool: light, readable, and genuinely useful. The center-finding scale saves time, the vials read true, and the non-marring body makes it safe on finished surfaces. It won’t replace a full-length, rigid box level for long runs or heavy jobsite abuse, and it doesn’t have magnets or metric. But as a compact, go-anywhere level-meets-ruler for hanging, layout, and small installs, it’s become a fixture in my kit.

Recommendation: I recommend it for anyone who needs a reliable, compact level and ruler in one—especially for finish and household tasks. The accuracy is solid, the usability is high, and the size means you’ll actually keep it within reach. Just be mindful of the slight flex on uneven surfaces and verify the printed scale against a reference before a precision job.