Superior Labs 3 1/8" Cessna Mechanical Tachometer SL1010-55004-14-N00 (A/C Model). Superior Labs (SLI) is the aircraft tachometer of choice by many OEM’s due to its precision and reliability. The Superior Labs 3 1/8" Cessna Mechanical Tachometer SL1010-55004-14-N00 has a Multiple Width Green ARC of 2000-2550; 2550-2650; 2650-2750, a Red Line of 2750 records at 2566. SLI also offers precision aircraft tachometers for aftermarket replacement for most single engine aircraft. SLI manufactures aircraft tachometers for all general aviation aircraft types and offers custom screen printed dials, internal lighting, anti-glare glass, and pre-set engine hours. This specific unit replaces Cessna P/N 150 (OLD) C668020-0201 Models.