Trimming and edging are tasks we can’t avoid whenever we want that beautiful look of our gardens. The ease to do it is another consideration that many of us will opt for. We feel BLACK+DECKER LST420 Trimmer and Edger will provide you with that solution for that specific need.

When you’ve got lots of trimming to do, you need the runtime to get it done. A dual-mode switch on the LST400 series cordless string trimmers gives you the option to choose between high power or up to one hour of extended runtime.

Delivering long battery life and power to tackle trimming and edging tasks, the BLACK+DECKER LST420 offers the freedom of cordless convenience and extended runtime. The LST420 features a new dual-mode switch, giving you the option to choose between high power or extended run time. You’ll get up to one hour of runtime1 for trimming large yards without the hassles of gas-powered trimmer/edgers.

Product Highlights

    • The PowerDrive Transmission delivers more power from the motor to the cutting string
    • Runtime Extension Technology with dual mode accelerator switch for high performance or longer run time
    • The Automatic Feed Spool ensures continuous work without bumping and having to stop to adjust the spool
    • Includes (2) 2.0 Amp hour lithium battery packs- each battery pack delivers 33% more capacity than the LBXR20 battery pack that gives you 2x more run time
    • Part of the 20V MAX System – A System Demands Attention. 1 Battery fits multiple tools
    • Product dimensions 7.2x 4.9x 43 inches
    • Products weight 8.2 pounds
    • Quiet and easy to start, delivering great cutting results without the mess and hassles of gas powered trimmers
    • Adjustable height and pivoting handle positions provide maximum comfort and control
    • 7200 / 5500 RPM
    • 12 in. cutting swath
    • Compatible with AF-100 trimmer lines

Ideal for trimming areas of overgrowth after mowing and edging along borders, sidewalks and flower beds, the LST420 is quiet and easy to start. The adjustable height and pivoting handle positions provide maximum comfort and control.



BLACK+DECKER’s Extended Runtime Technology features electronics that allow this trimmer/edger to maintain constant speed in a variety of grass conditions so the it runs at an efficient speed for extended battery life. In high-power mode, the LST420 ramps up the power output to quickly take down heavy grass and weeds. In runtime mode, the trimmer/edger provides up to one hour of runtime for normal trimming helping to maintain cutting performance while trimming and edging in heavy grass or weeds. That ultra-efficient performance plus a generous 12-inch cutting swath help every job go faster.

The LST420 comes with two 2.0 amp-hour lithium-ion batteries (model LBXR2020), which offers 33 percent more runtime per battery pack than the previous LBXR20 pack. BLACK+DECKER’s 20-volt MAX lithium-ion batteries offer a longer lifespan and retains its charge 5x longer than similar 18-volt NiCad batteries. They’re compatible with the full line of BLACK+DECKER’s 20-volt MAX line of power and gardening tools, and you won’t be limited by an extension cord

This cordless trimmer/edger also features BLACK+DECKER’s PowerDrive Transmission, With the LST420, you never have to bump to release the string or waste time continually adjusting the string spool. The BLACK+DECKER Automatic Feed Spool keeps the string at the optimal length automatically and continuously. The LST420 also converts from trimmer to an edger in seconds. A wheeled edge guide has been added for balance, helping to eliminate the need to hover the trimmer/edger over the line of grass between the lawn and sidewalk while edging. Simply roll along the sidewalk or driveway, and the wheel supports the weight of the trimmer/edger for a fine edge and straight, clean edges.


  • The 420 series has the Runtime Extension Technology with dual-mode accelerator switch for high performance or longer run time. It also has up to one hour of runtime when using dual mode switch in run-time mode.
  • It’s very light compared to gas powered trimmers.
  • It weighs about six pounds, the handle length adjusts easily to your height making it very easy to use.
  • The trimmer can be rotated so that it performs as an edger (which allows the orange wheel at the bottom of the trimmer to be rolled along a flat surface).
  • Assembly is real easy and consisted of pushing the plastic guard into a slot (1 screw) and attaching the D shaped handle (1 bolt).


  • The operating thumb button could be a better design. While I see the safety in having to pull one button with your thumb while gripping the other button on the handle, it does get a bit tiring.

Our Opinion

Very happy with overall function and performance, battery recharge times, adjustable shaft length, ease of cutting unit rotation, and the edge rolling wheel guide are just plain smart engineering.

If you are looking for a reliable trimmer and edger look no further than BLACK+DECKER LST420 Trimmer and Edger for it will be a perfect solution to that need you have. It is one of those few trimmers we can We highly recommend this product for you.

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