TempTraceTemperature Recorders combine an unbeatable combination of durability, accuracy and affordability. The Temperature Recorders are portable, simple to use and provide a permanent 7-day record of temperature trends in a selection of ranges. Small 4" diameter chart size increases portability and allows installation in most sizes of temperature shelters. The Temperature Recorder SL4 adds a convenient digital display for quick monitoring checks. Each unit includes one AA battery, pen, one box of 60 charts in an assortment of temperature ranges, and an instruction manual. Replacement Charts and Replacement Pens are sold separately.