Mutex Bathroom Door Lock Knob, Color Indicator for Vacant or Occupied in Use Restroom, Thumbturn, Emergency Unlock, Fits Standard 2 1/8" Doors - Amazon.com
1 set Stainless steel Privacy WC Latch Vacant Engaged Door Lock Toilet Shower cubicles & Bathroom Indicator Bolt Door lock - AliExpress
Universal Hardware Universal Hardware Occupancy Indicator Deadbolt, non-handed, adjustable backset, Satin Chrome Finish UH40131 - The Home Depot
Mutex+Bls2+Bathroom+Indicator+Privacy+Door+Knob+In-use+Occupied+or+Vacant+Nickel for sale online | eBay