Normal F Form
Double engagement (F flex-flex) for parallel and angular misalignment
Single engagement (FFR flex-rigid) accommodates angular misalignment only and it is best for floating shaft applications
Marketplace conventional flange bolt patterns
FHD Variety common for sizes 10 via thirty (other sizes available upon request)
Rigid-Rigid FRR Kind
Built for connecting two rigidly mounted shafts without misalignment capability
Alloy Rigid-Rigid FARR Form
Longer piloted hubs sustain 
rigidity and concentricity
Made use of for cantilevered loads for example gear boxes that hang off conveyor techniques
Alloy steel out there for better power (FARR)
Mill Motor FMM Type
To start with hub intended with longer universal hub on one end to accommodate straight or tapered shafts
2nd hub bored to purchaser specs
Normal style and design accommodates AISE Mill Motor frame sizes
Sleeves and second hub are common