The Koenig Expander Plug is a unique system to seal holes with absolute integrity in various types of hydraulic and pneumatic components such as controls, valves, regulators, relays, cylinders, motors, presses, pumps, where hydraulic fluid or gaseous medium under pressure flow through channels in the device. These channels must be drilled from outside to connect internal passages. These drilled holes must then be sealed pressure tight to operate the device and prevent leaks. A number of other sealing methods can be used but can often be more costly and less reliable.

The Koenig Expander Plug provides a safe, quick, leak-proof, and low cost method for sealing cross-drilled holes. It ensures peak performance with a comfortable safety margin even in extreme applications. They are available in five styles and in different materials.

Extremely versatile and available in a variety of materials the Koenig Expander permanently resists even the most extreme loads and pressures. Originally designed for use in hydraulic assemblies, it is now well established and used in various industries especially automotive, fluid power and commercial / plant vehicles.


The Koenig Restrictor offers flow control and pressure regulation with its precision drilled outlet. The Restrictor employs Koenig Expander technology, utilizing the expansion principle for easy integration into channel systems for unsurpassed reliable flow control.

The Koenig Restrictor is a precise orifice and cost-effective engineered solution to restrict flow in fluid systems. The one-piece expansion Koenig Restrictor easily installs into an as-drilled hole.


The Koenig Check Valve adds significant value to the flow control system. The Check Valve controls flow directions in fluid systems. Not only simple to install, Koenig produce check valves with optimized cracking pressures to suit customer specific system requirements; facilitating complete design control.

MB Series Koenig Expander