Rectorseal GDLSLO3500S 4.57" Square Lockout Floor Drain - SRectorseal GDLSLO3500S The Guardian Lockout prevents foul odors and bugs from exiting the pipes and eliminates the need for a primer trap. The center bolt locks the grate in place, solving the problem of missing or sheered screws. The fully assembled one piece unit is easy to install. Features CLOG, ODOR BUG PROTECTION: Protects commercial floor drains from unwanted debris clogging pipes and backing up plumbing lines; features odor and bug blocker