Socket head cap screws have a round cap with hex socket (Allen) drive.  The screws are tightened with a hex key or allen wrench.  Commonly found in machine assembly where you do not have enough space to tighten with a wrench or socket.  Socket head cap screws can withstand more torque than a button head or flat head socket cap screw because of the deeper drive.  Black oxide is the most popular finish, but socket head cap screws also come in zinc and stainless steel.

Button head socket cap screws have a hex socket (Allen) drive.  The screws are tightened with a hex key or allen wrench.  Commonly found in machine assembly where you do not have enough space to tighten with a wrench or socket.  Black oxide is the most popular finish, but button head socket cap screws also come in zinc and stainless steel.

Flat head socket cap screws have a hex socket (Allen) drive.  The screws are tightened with a hex key or allen wrench.  Commonly found in machine assembly where you do not have enough space to tighten with a wrench or socket.  The flat head allows this socket cap screw to sit flush with the surface.  Black oxide is the most popular finish, but button head socket cap screws also come in zinc and stainless steel.

Socket shoulder (Stripper) bolts have a hex socket (Allen) drive and a cylindrical head.  The shank or shoulder on the top of the socket shoulder bolts have a smooth finish to allow for rotation of pulleys, linkages, and moving parts.  These bolts are commonly found in mechanical applications, engines, and moving wheels.  There are narrower threads underneath the shank/shoulder of the bolt.  The stripper bolt term is used when the bolt is attached to a stripper plate.  Steel and stainless options are available for the material and imperial and metric options are available for sizing.

Socket set screws are a headless fastener which usually sits flush or just below the surface of the application.  They are designed to secure pullys or machine parts to shafts.  Cup point set screws dig into the contact surface for a secure connection.  Flat, oval, and soft-tip set screws are used for minimal contact of the surface for a wide range of applications.  Extended-tip (Dog Point) set screws have an extended tip allowing it to fit into a mating hold or slot.  Cone point set screws have a pointed tip allowing it to grab into softer materials like brass.  Swivel tipped set screws allow for a constant connection with  an angled or uneven surface.  There are a variety of materials on socket set screws including alloy steel, stainless steel, brass, and nylon.