Typically used when mounting something like a motor to a pump, gearbox, etc.
One will be needed for the shaft of your motor and one more for the shaft of the pump along with the spider to combine them as shown in the example picture.
These are L095 size couplings.
The spider is made of Hythrel and is oil resistant and provides 2.5 time the torque capacity over Buna & Urethane spiders.
