The CL390’s AC/DC measurements with an extra bottom display, for electricians who often read a meter at an awkward angle.
Amazon $101.66The Klein Tools CL490 is the better clamp meter overall, rated 3.7 to 3.4. The Southwire 21550T costs $11.09 less ($90.57 vs $101.66).
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.
A true-RMS AC/DC clamp with handy jobsite touches, for electricians who don’t need inrush or a CAT IV rating.
Amazon $90.57Scores 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 weight | Klein Tools CL490 | Southwire 21550T |
|---|---|---|
| Overall rating | 3.7/5 | 3.4/5 |
| Current range 15% | 46 400 A through the jaw | 46 400 A through the jaw |
| DC current 15% | 100 DC current to 400 A through the jaw | 100 DC current to 400 A through the jaw |
| Safety rating 20% | 55 CAT III 600 V | 55 CAT III 600 V |
| Features 15% | 50 true RMS, non-contact voltage, temperature, DC microamps | 45 true RMS, non-contact voltage, temperature |
| Accuracy 10% | 67 2% of reading | 50 current accuracy not published (neutral score used) |
| Jaw opening 5% | 70 41 mm jaw | 50 jaw opening not published (neutral score used) |
| Warranty 10% | 50 2-year warranty | 0 warranty not published, scored as none |
| Price 10% | 69 $101.66 | 74 $90.57 |
Specifications
| Klein Tools CL490 | Southwire 21550T | |
|---|---|---|
| Measurement | ||
| AC current (jaw) | 400 A | 400 A |
| DC current (jaw) | 400 A | 400 A |
| DC microamps (leads) | 200 uA | - |
| Voltage | 600 V | - |
| Current accuracy | 2% of reading | - |
| Jaw opening | 41 mm | - |
| Safety | ||
| CAT rating | CAT III 600 V | CAT III 600 V |
| Features | ||
| True RMS | Yes | Yes |
| Inrush | No | - |
| LoZ mode | No | - |
| Non-contact voltage | Yes | Yes |
| Low-pass filter | No | - |
| Temperature | Yes | Yes |
| Phone app | No | - |
| Build | ||
| Weight | 346 g | - |
| Warranty | 2 years | - |
