The 2001-SRN (sometimes referred to as a 2001-DC) was an electromechanical siren by the Federal Signal corporation and is the earliest model of the 2001 series. It can be differentiated from other 2001 sirens by its rotator box.
The 2001-SRN was introduced in 1988 to replace the aging Thunderbolt series, as demand for battery backup required a new design. The 2001-SRN reused the Thunderbolt's rotator, giving the 2001-SRN its unique look. Later 2001 series sirens switched to a smaller direct-drive square rotator box. The siren was discontinued around 2002, being replaced by the 2001-SRNB which used the smaller rotator.
There are a few models of 2001-SRNB. The earliest models used a round rear housing, which was more expensive to produce. These are the rarest models of 2001, as they were only sold between 1988-1990 before being replaced by the more common square housing. These 2001s are known as "roundback" 2001-SRNs. In 1998, the 2001-SRN recieved another design update which gave it a larger, improved motor cover and stator design with a small Federal Signal logo on it. These were sold until 2002 when the 2001-SRN was discontinued.
The 2001-SRN produces 126Db at 100 feet, the quietest of the 2001 series. This is due to a support beam partially blocking the chopper intake. This design flaw would not be fixed until the 2001-130.