Bill Kasselman has been selling metal detectors for the last 45 years.
He showed me the many settings that walk-through metal detectors can be tuned to. Crank up the sensitivity, and you can detect small coins, zippers and buttons.
Kassleman says most walk-through detectors aren't set that way for timing purposes. They are set to a lower sensitivity to detect larger metal found in guns and weapons.
That also cuts down the screening time.
While some districts aren't convinced that metal detectors are the best investment in stopping weapons from coming in, other districts like Santa Fe ISD, are installing 19 of them this year.
Aldine ISD has about 200 metal detectors. The district has seen a dramatic decline in weapons seized since 2010.
In 2016, there were only two weapons confiscated. The process also includes checking backpacks.
"We check backpacks every day. We check purses. It's just as if you were gong to Minute Maid or Reliant Stadium," said Aldine ISD Assistant Superintendent Ken Knippel.
Critics of the detectors say security wait times outside of school pose a safety issue. Aldine ISD students wait about 30 minutes each day in those metal detector screening lines.
Metal detectors are used at random at Cy-Fair ISD. In July, the district announced that middle and high school students will be required to have clear backpacks.
Having clear bags will make it easier to cut down on the wait times. Those clear bags are also mandatory for everyone attending sporting events at Cy-Fair stadiums.
Elementary school students will still be allowed to use regular backpacks.
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