Woot offers U.S. Patrol Keep Closed for Maximum Lock Ideal Stopper for $24.49 (orig. $34.99). Free shipping for Prime Members.

Product Description:
Window Lock Bar Sets - Extra Home Security - Easy to Install AdjustableNeed some extra security?Add some decorative window lock bars designed to dress up windows while keeping your home secure.Durable construction ensures long-lasting protection. They're easy to install and adjust to fit window openings. Set of 2 to fit any décor.Additional Info: 2.5 pounds each.Dimensions: Adjust from 12-21. 

• SUPPLEMENTAL SECURITY: When the window lock just isn’t enough, use the sliding window bar for extra home security
• DURABLE: The iron construction provides reliable durability for maximum security
• DECORATIVE DESIGN: The leaf pattern provides a decorative flare to your home
• EASY INSTALLATION: The lock bar can easily be placed and removed at your convenience
• SECURITY BAR'S ADJUSTABLE SIZE: The window stopper can be adjusted between 12”-21”. This window safety bar provides the ideal window stopper for optimal peace of mind