Now residents in Lafayette, Louisiana can get a little something extra when they’re checking out “Harry Potter and the Cursed Child”: The library system recently acquired 12 Speck air quality monitors and are making them available for loan to library cardholders.

The Speck monitors were developed by Carnegie Mellon University and built by Airviz, after introducing them at the SXSW Interactive Festival in Austin, Texas. The monitors were designed for home use and feature a display that shows indoor air quality.

According to KATC-TV in Lafayette, library card holders can check out the units for three weeks at a time. That way, library patrons can determine indoor air quality (IAQ) in their homes.

“We are making these Specks available in our libraries to give the tools to our patrons to make better decisions in their homes and, hopefully, make their home environments healthier,” said Teresa Elberson, Lafayette Public Library Director. “We’re excited to partner with Carnegie Mellon and Airviz to make this possible.”