The Milwaukee Police Department (MPD) announced that all police districts city-wide have been outfitted with bullet-resistant glass in the lobbies.

The investment was covered by several private donors, including former Milwaukee County executive Chris Abele, Dennis Klein and Frank P. Crivello, founder and chairman of Phoenix Investors. According to news reports, the cost of the glass and installation is $261,000. B&D Contractors installed the glass.

“This is not a one-time deal,” said Mark McClain of the Milwaukee Police Foundation. “We’re going to continue to work with the community to find safety measures from the community side as well as from the law enforcement side.”

The news comes five months after a gunman opened fire inside an MPD district building. Darreon Parker-Bell is accused of shooting a gun within a police station in February. No one was injured in the incident.

Bullet-resistant glass was created to withstand one or many rounds of bullets depending on the weapon and thickness of the glass. The glass is designed to reduce the velocity by absorbing the energy from the bullets. However, bullet-resistant glass is not fully impenetrable. Deadly weapons with high-speed bullets can penetrate even super thick bullet-resistant glass.

Companies such as Armoured One exhaustively test their glass to ensure maximum protection. Armoured One utilizes Filti Testing & Development and a third-party observer for its testing procedures. The test begins with 10 .223 rounds fired from an AR15. After the glass is shot, it’s struck twice with a 100-pound ram at 50-foot pounds of force. If the ram penetrates the glass before the two hits, the glass is deemed a failure.