Amesbury Truth 13183 Combination vent lock / security night latch for vinyl windows.
Pop-Out Feature is easy to use and provides additional security.

When properly installed, this limit device restricts single hung or double hung, horizontal or vertical opening window sash from opening more than four (4) inches 

Face Width: 1/2 inch
Bottom Width: 3/8 inch
Face Length: 2-1/8 inch
Bottom Length: 2 inches
Depth: 5/16 inch
Material: Plastic 
Priced and sold each.

Color Options:
White
Cameo
Tan
Desert Tan
Faux Oil Rubbed Bronze 

Normally installed in pairs, the spring loaded  restrictor can be in the retracted position for normal operation  or extended to provide air circulation when window is open and offer some security from unwanted intruders.

NOTE: When the window is opened to fast, and the limit device is extended,  it may result in the night latch being broken. To remove old night lock, use pliers to grab the extended restrictor and give it a sharp tug. 
The replacement, when positioned correctly,  will push back into the hole and you are good to go.  
* Check to be sure you have the latch positioned correctly before installing.