FitBest Carburetor for Zama RB-K90 fits Echo PB-251 PB-255 PB-255LN ES-255 Blowers Brand new high quality aftermarket Carburetor Replaces zama RB-K90 Fits Echo PB-251 PB-255 PB-255LN ES-255 Blowers Replaces part numbers A021001590 A021001591 A021001592 A021001593