Klein Tools CL390 vs Southwire 21550T

Last updated: November 9, 2026

The Klein Tools CL390 is the better clamp meter overall, rated 3.7 to 3.4. The Klein Tools CL390 costs $4.30 less ($86.27 vs $90.57).

Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.

Klein Tools CL390 vs Southwire 21550T

Scores side by side

Each factor is scored 0-100 against the same fixed reference points for every AC/DC clamp meter; a clear win is highlighted. How we rank explains each one.

Factor weightKlein Tools CL390Southwire 21550T
Overall rating3.7/53.4/5
Current range 15%46 400 A through the jaw46 400 A through the jaw
DC current 15%100 DC current to 400 A through the jaw100 DC current to 400 A through the jaw
Safety rating 20%55 CAT III 600 V55 CAT III 600 V
Features 15%50 true RMS, non-contact voltage, temperature, DC microamps45 true RMS, non-contact voltage, temperature
Accuracy 10%67 2% of reading50 current accuracy not published (neutral score used)
Jaw opening 5%70 41 mm jaw50 jaw opening not published (neutral score used)
Warranty 10%50 2-year warranty0 warranty not published, scored as none
Price 10%76 $86.2774 $90.57

Specifications

Klein Tools CL390Southwire 21550T
Measurement
AC current (jaw)400 A400 A
DC current (jaw)400 A400 A
DC microamps (leads)200 uA-
Voltage600 V-
Current accuracy2% of reading-
Jaw opening41 mm-
Safety
CAT ratingCAT III 600 VCAT III 600 V
Features
True RMSYesYes
InrushNo-
LoZ modeNo-
Non-contact voltageYesYes
Low-pass filterNo-
TemperatureYesYes
Phone appNo-
Build
Weight291 g-
Warranty2 years-

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