This coupling provides a crucial advantage: coupling misalignments of the motor to the propeller shaft of up to 2° can be compensated. This makes the installation of the motor much easier. With a 2° misalignment , the maximum shaft speed of 1500 rev / min may not be exeeded. The couplings are provided with mounting holes for 4 inch and 5 inches mounting flange. You can install the coupling with clamping hub. Does not work with V drive. Find the right coupling in three steps. 1st step: First check the engine horsepower. 2nd step: What is the reduction ratio? Here is an example using a 40 hp engine with 3600 rpm and a reduction ratio of 2:1. Step 3: Calculate as follows: 3600 rpm / 2 (reduction ratio 2:1) = 1800 rpm / 100 rpm * 5.3 (load capacity of the coupling) = 50.4 hp max. power. UNIFLEX 12 coupling is therefore suitable in this case. Overview table