Common F Style
Double engagement (F flex-flex) for parallel and angular misalignment
Single engagement (FFR flex-rigid) accommodates angular misalignment only and is great for floating shaft applications
Business common flange bolt patterns
FHD Sort typical for sizes 10 as a result of thirty (other sizes readily available on request)
Rigid-Rigid FRR Style
Intended for connecting two rigidly mounted shafts with no misalignment capability
Alloy Rigid-Rigid FARR Variety
Longer piloted hubs keep rigidity and concentricity
Utilized for cantilevered loads for example gear boxes that hang off conveyor programs
Alloy steel out there for better strength (FARR)
Mill Motor FMM Kind
1st hub built with longer universal hub on a single finish to accommodate straight or tapered shafts
Second hub bored to purchaser specs
Regular style and design accommodates AISE Mill Motor frame sizes
Sleeves and second 
hub are regular