T1708 E-Thru trainer axle M12x1.75, with standard threaded cartridge. Suitable for hubs with a Maxle axle skewer attachment 135×12, 142×12, 150×12 mm and Trek 

T-1711 M12X1.0  -  fits most Felt bikes, This guy does 142x12 as well as 148x12 so is the long version

T-1707  fits most Felt bikes, This guy does 142x12 ONLY so does not do 148x12 it is the short version used mainly on road bikes