Alarm Lock’s PG21 Series Narrow Stile Door Alarms have long been an industry staple in all applications, from retail, to firms, to institutions and schools. And now the best, just got better! The New & Improved PG21 MS Series Door Alarms have new features and a new Designer Look that fits both standard size and narrow stile doors. The new Strobe Option for sight and sound upon alarm is a necessity when time is so critical in apprehending a perpetrator making an unauthorized exit. Now security staff can audibly and visually pinpoint which door, across the floor, even among a whole bank of doors, has been violated faster than ever.