KHS Flat needle roller cages consists of FF and FF..ZW series which are plastic ,with dovetail notches on the ends which enable any number of components to be fixed end to end .The needle rollers are grouped in a diameter tolerance of 0 to -2 microns ,and are individually guided and retained.KHS flat cages prevent “slip-stick” and ensure smooth trouble free running running for all types of flat guidways.FF series are single row flat cage and FF..ZW are double row flat cage. The double row are connected by a flexible web which permits the two rows of needle rollers to be bent to any required angle relative to one another so that the whole can be used as a inverted vee-cage. (series includes FF,FF..ZW..etc.)