2001SRNB
The 2001SRNB was the second generation of Federal Signal Corporation's 2001 series. Its design is similar to the original. The most important change is a refined stator design, upping the sound output to 128db Secondly, a new gear-driven rotator replaced the belt-driven rotator originally from the Thunderbolt. These models can be identified by the 2001SRNB text on the rotator.