The rubber in the isolator acts as a spring. It is very soft laterally but very stiff vertically. The high vertical stiffness is achieved by having thin layers of rubber reinforced by steel shims. These two characteristics allow the isolator to move laterally with relatively low stiffness yet carry significant axial load due to their high vertical stiffness. The lead core provides damping by deforming plastically when the isolator moves laterally in an earthquake.

Isolators from 12 to 60 inches in diameter and capacities of up to 4000 tons are manufactured. Custom dimensions are available for special applications.

The shims for isolators are cut to exacting tolerances by laser. The steel mounting plates are machined by computer controlled milling machines that give high production throughput and accuracy. Molding each bearing takes 8 to 48 hours depending on the size of the bearing. The curing phase is continuously monitored to ensure that the rubber is uniformly cured throughout the bearing.