Insulated Male Bullet Connectors also known as male bullet terminals are electrical connectors used to easily connect and disconnect wires without tools. 

They consist of a metal pin (the male bullet) and an insulated sleeve, often made of vinyl or PVC, that comes in different colors to indicate wire size. 
To use, the metal part is crimped onto a stripped wire, and the insulated sleeve provides protection and grip. 
They connect with female bullet connectors to create a secure, removable electrical connection. 
Commonly used in automotive, electronics, and general electrical wiring applications. 
Different sizes are available to accommodate various wire gauges. 
The color of the insulation usually indicates the wire size it fits.