RSF83Y100R is a compact external level switch designed for mounting through tank walls via 1/2" NPT thread without requiring internal tank access. Constructed from nylon with black color, it operates over a temperature range of -20°C to +75°C and accommodates fluids with a minimum specific gravity of 0.85. The switch features a must-close level of 7 mm and must-open level of 20 mm (at SG=1), with selectable make-on-rise (N/O) or make-on-fall (N/C) operation by 180° rotation. Electrically rated for 25 VA maximum switching power at 240 V AC or 120 V DC with a maximum switching current of 0.6 A, and includes 100 cm of PVC flying leads (16/0.2 gauge). This device is ideal for monitoring diesel generator fuel levels, hydraulic oil, and gearbox oil levels in industrial and mobile applications, with WRAS approval for water system compatibility.