"This is super cool;" "I've never seen anything like it;" "How do I get my hands on one?" Talk to NVIDIA recruiter Lisa Calderon and she'll tell you she has a secret weapon when it comes to getting tech's top talent talking to her. It's a foot long, one-and-a-half inches wide and covered with - to the uninitiated - strange gold markings. "Everyone asks the same thing," Calderon says. "'Can I have one?' And, of course, 'can I take another one for my 'friend'?'"

It's the NVIDIA ruler. And, as many NVIDIANs have learned, taking this modest slab of PCB board to the right place - and showing it to the right people - gets an immediate reaction. "Every electrical engineer that I've showed it to has instantly said 'I need one of these right now,'" says Josh, an NVIDIA ASIC architect, who has mailed bunches of them to contacts around the industry. Each time the ruler appears at NVIDIA's internal company store - which has sold 5,000 of these rulers so far - it sells out in minutes. Thousands more have been snatched up at industry conferences such as NIPS - the long-running deep-learning conference - where its appearance created a social media sensation. Employees at competitors will sidle up to our booth at industry events to trade bundles of their swag for it. It's never been made available to the public. But, if you're quick, you can find one on eBay for 10 times its modest employee-only price of $3.50 (when it's available). The only sure to way to get one: make friends with someone at NVIDIA.For Engineers by Engineers
The story behind NVIDIA's least likely cult product began in 2016 with VP of Hardware Engineering Andrew Bell, a 15-year veteran of the company. Bell wanted something engineers could slip into their back pocket and take with them to design meetings.

The motivation, Bell explains, was that many of the interns and new college graduates NVIDIA hires come from working in the digital world, where the physical size of things is hard to understand. Weaving a GPU into the mesh of inductors and capacitors, diodes and crystals held together by these boards takes sweat, a steady hand and a good soldering iron. The rule would be a training tool to calibrate people's digital world to the real world, to avoid using components that were too large, or too small, for a design, Bell says.

Creating that tool quickly became a labor of love, explains John, a NVIDIA engineer whose job is to manage the many complex tools engineers used to source parts and put them to work. John teamed up with Andy, a veteran systems engineer, who designed the schematic for the ruler using some of the same electronic design tools used to build NVIDIA's other products, and Oscar, who did the ruler's layout.

What makes the NVIDIA ruler unique, the pair explains, is that unlike other rules that reference the most widely used parts, the NVIDIA ruler shows the parts engineers at NVIDIA most often use to put together the company's products. That includes the formidable GP104 GPU found in our graphics cards for gamers and the Tegra X1 and K1 mobile processors, or SoCs as they're known in industry parlance. They not only give engineers the ability to see at a glance each part's size, they show crucial details, such as the position of the scores of ball grid arrays that need to be carefully aligned with the pins on the back of each processor to bring them to life.NVIDIA's flagship products are just the highlights on a ruler that's packed with details. And talking with John and Andy about them is a fascinating crash-course in their craft. Take the series of holes that increase in size from bottom to top at the center of a table on one end of the ruler. A validation engineer, Andy explains, can use it to measure the diameter of a wire. The engineer can then refer to another table on the ruler - complete with a handy formula - to calculate resistance per unit of length so he or she can solve for what diameter of wire you need for a board, and know how many volts you'll drop when you carry a certain amount of current through it.

The ruler itself is a remarkable work of craftsmanship, too. It's made from a printed circuit boards, the multi-layered sandwiches of fiberglass and copper foil that connect the electronic components inside just about every electronic gadget. The gold markings are left by the same electroless nickel immersion gold, or ENIG, plating process used in many electronic components. The final product is manufactured by a small shop in Silicon Valley with a long track-record of creating custom circuit boards.

But it's one that quickly gained a cult-following inside the company when it was first revealed on the NVIDIA's lively "cross-discipline discuss" internal email alias in September 2016. "That looks like an absolute ruler to me," one engineer wrote when a picture was first posted. "This totally rules!" another wrote. Word got out fast. Within hours of the first public giveaway at an elite East Coast tech school, an image of the ruler was posted online where it was viewed more than 78,000 times. The most common comment? "I want one." One of the most common questions? "Does it play Crysis?"Asked to explain the passion among NVIDIA's thousands of engineers - many of whom labor in computer-assisted design tools far away from the nit-and-grit of putting products together - for a tool designed to aid the work of just a few hundred, John has a simple explanation. "I know people who look at it and say 'I worked on this chip, I really want this,'" John says. "Anyone at the company who has done any work on any of these chips would think of it as a souvenir they would want to have."

It is, in short, a 12-inch piece of NVIDIA's soul.