BOULDER, Colo. -- The search continues for hard-to-find solar eclipse viewing glasses that are mandatory for Monday's event.
People have been going store to store all over the Denver metro area trying to land a pair before Monday's solar eclipse.
Several thousand pairs have been distributed by schools, universities, libraries, museums and Walmart, but most have run out.
With the supply drying up, a hardware store in Boulder got a last-minute shipment of 2,000 glasses and sold them out in less than two hours Friday.
Several people lined up at McGuckin Hardware at 2525 Arapahoe Ave. when it opened at 7:30 a.m., hoping to get a pair.
The shipment arrived about 9:30 a.m. and the store started selling the glasses to those waiting in the long line. They were sold out before 11:30 a.m.
Not long ago, McGuckin Hardware had more than 32,000 eclipse glasses in stock. But that supply quickly dried up as the eclipse got closer.
The glasses cost $4 apiece and there was a limit of four per customer. The store said the glasses meet all of the certification requirements for safety, but the supply is not expected to last long.
Eye doctors stress that it's too risky to try to sneak even a quick peek at the sun with the naked eye. The proper protection is imperative to avoid permanent vision problems.
Glasses must have the proper ISO code 12312-2 (sometimes written as ISO 12312-2:2015) to be legitimate to use for the eclipse.
Filters that are ISO 12312-2 compliant reduce visible sunlight to safe and comfortable levels, and block solar UV and IR radiation.
Monday's eclipse will be the first to go coast to coast across the U.S. in 99 years. The path of totality will cut across Wyoming and Nebraska, where up to 500,000 people are expected.
Denver will have about 92 percent totality with more totality the farther north.
RELATED: Map shows what solar eclipse will look like across the country
RELATED: Interactive map of how the eclipse will look
RELATED: Where to see the solar eclipse
RELATED: What the solar eclipse will look like by ZIP code
RELATED: How to make a DIY solar eclipse viewer at home
RELATED: What not to do during a solar eclipse
RELATED: Tips for taking photos of solar eclipse
RELATED: Avoid buying bogus eclipse glasses