Defender Security Door Knocker & Viewer for $9 + free shipping w/ Prime
Published Date: 7/30/2021
Source: dealnews.com

That's the best deal we could find by $3. Buy Now at eBay

Tips
  • In Satin Nickel.
  • Sold by Zoro via eBay.
Features
  • requires a 9/16" diameter installation hole
  • 160° viewing angle
  • Model: ‎U 10327