Greenworks 40V 12-Inch Cordless String Trimmer BST4000 — Front-Mount Motor, Variable Speed

The Greenworks 40V 12-inch cordless string trimmer (BST4000) is a lightweight, front-mount motor trimmer that delivers a 12" cutting path and variable-speed control for easy, gas-free edging and weed trimming.

Built for homeowners who want the power of battery tools without the fuss of gas, the Greenworks G-MAX 40V system pairs a compact 12-inch cutting head with an ergonomic design. The BST4000 uses a front-mounted motor for balanced handling, an auto-feed .065" line head to reduce stops, and a variable-speed trigger so you can dial power to the task. Battery and charger are sold separately and are compatible with Greenworks G-MAX 40V batteries.

How does the BST4000 make trimming easier on the body?

The trimmer is designed to be noticeably lighter than gas counterparts and positions the motor at the front to improve balance and reduce wrist strain. Its ergonomics and trigger placement let you work longer with less fatigue.

• Ultra-lightweight housing for reduced arm and shoulder strain
• Front-mount motor for better center of gravity and control
• Comfortable handle and intuitive trigger placement
• Variable speed for matching power to the task and saving battery life

What cutting performance can I expect from a 12-inch head?

The BST4000’s 12" cutting path is sized for typical yards, flower beds, and around walkways. With .065" line and an auto-feed head, it clears grass and light weeds quickly while minimizing downtime for line advancement.

• 12-inch cutting swath for efficient passes around lawns and edges
• .065" diameter cutting line for consistent trimming performance
• Auto-feed head advances line easily without bumping or manual threading
• Variable speed to handle thin grass up to thicker weeds

Which batteries and conditions work with this cordless trimmer?

The trimmer runs on Greenworks G-MAX 40V lithium-ion batteries (models 29472 and 29462) and uses charger 29482; the kit is battery- and charger-free so you can add the appropriate G-MAX pack. Recommended operating temperature ranges ensure reliable starts and safe charging.

• Compatible with G-MAX 40V batteries 29472 and 29462 (sold separately)
• Use Greenworks charger model 29482 for optimal charging
• Trimmer operating range: 6.8°F (-14°C) to 104°F (40°C)
• Charger operating range: 39°F (4°C) to 113°F (45°C)

How simple is maintenance and routine use?

The BST4000 minimizes upkeep by eliminating gas mixing and spark plugs; the auto-feed spool reduces time spent reloading line. Routine tasks are limited to keeping the spool loaded, occasional cleaning, and using the correct battery and charger.

• No gas, oil, or carburetor maintenance—battery power only
• Auto-feed head simplifies line advancement and replacement
• Wipe down after use and clear debris from the guard for longevity
• Store with battery removed and keep spool covered to protect line

Who this is for: The Greenworks BST4000 is aimed at homeowners and property keepers who want a balanced, lightweight cordless trimmer for routine lawn care, edging, and trimming around beds and paths. It’s a good fit for those who already own or plan to buy Greenworks G-MAX 40V batteries and prefer low-maintenance, emission-free tools that deliver dependable cutting for small to medium yards.