Prologic electronic alarms and visual indicators complement each other. SNZ Slim and Chubby hangers show line movement; the Chubby lets you choose between free movement through the ball clip and a more fixed line position. Extra weight helps adapt the indicator when distance or wind calls for greater line tension.
A single alarm or a complete set?
The blue C-Series Non-Wireless is a standalone alarm: do not expect wireless receiver functionality. The C-Series sets in this selection combine alarms, a receiver and a bivvy light. R2L uses an infrared sensor with a line roller and has dedicated drop-back indication. Check the alarm count and battery requirements of each set; a hanger or swinger is not itself an electronic bite alarm.
See also: Prologic.
Compare the full range: Bite Indication.