It looks like a taxi, acts like a police officer, and you won't find it anywhere in York County but Mudhook Brewing Co.

Bolted to the wall in the York City brew pub is a bright-yellow device that invites patrons to insert a $1 bill, wrap their lips around a disposable straw and blow for five seconds.

The inventors of Know UR Limit claim the machine will produce an accurate reading of a person's blood-alcohol content -- a measurement folks usually encounter only after being pulled over on suspicion of drunken driving.

Even though most people who use the device do so out of curiosity, some patrons have taken advantage of the knowledge it dispenses, said Mudhook owner Jeff Lau.

"You sit down and have three of our Belgian Dubbels. It's 7 percent alcohol," Lau said. "You sometimes question whether you should be driving."

The alcohol-level analyzer has greeted Mudhook patrons near the pub's bathrooms for about three months. Lau said he got a visit from a Lancaster man willing to install the

device for free and split the proceeds going forward.

That sounded like a good deal, Lau said.

"It's kind of what's neat about our place. We're willing to try new things," he said.

The origin: Maryland-based inventor Greg Wilson said he began tinkering with the idea of the device about five years ago.

A friend of Wilson's from high school had died years earlier in an accident caused by a drunken driver.

Then, Wilson said, it happened again in 2009. The Hagerstown, Md., native lost a second friend the same way.

Wilson, 29, said he started working harder.

Today, the Know UR Limit company has about 200 devices in bars across the country. The final design uses an HVAC-like system to clear residual alcohol from the machine and produce an accurate reading every time.

"If it saves one person a year, I consider it a success," Wilson said.

Don't expect the Know UR Limit reading to spare you a DUI charge, however. The machines include a disclaimer: "For personal awareness only, not legally responsible for users' actions or machine accuracy."

So far, Mudhook has the only Know UR Limit machine in York County, said Jim Jeffries, who works to get the machines into Pennsylvania bars.

"I think Pennsylvania needs them. Everybody has a speedometer on their car because there's a speed limit. But nobody has a drinkometer except the police," Jeffries said. "I think the average bar patron needs a little help because they just guesstimate and most people tend to be overly optimistic."

-- Erin James may also be reached at ejames@yorkdispatch.com.