This deal has ended.
This 4-Pack Rosewill RSHS-11001 Home Security Indoor / Window Alarms drops from $24.99 to $14.99 to $9.99 with code AFNJ0662 at checkout. Plus, shipping is free. This is the lowest price we could find by $7. They feature a magnetic-triggered mechanism that alarms when the magnetic contact is broken. They also have a battery life of four-six months in standby mode. There is no sales tax (except in CA, NJ, TN).