Open compact orange case displaying the Klein 66040 5-piece impact set with four coaxial spring-loaded sockets and a 1/4-inch hex adapter.
Diagram detailing 8 SAE socket sizes in 4 coaxial bodies, 12-point high-torque design, and 1/4-inch hex to 1/2-inch square drive conversion.
Close-up of the Klein 1/4-inch hex shank to 1/2-inch male square drive adapter with spring-loaded retention ball detent.
Four 12-point coaxial sockets and drive adapter lined up to display laser-etched SAE size callouts and color-coded identification bands.
Perspective view of the open orange carrying case organizing four coaxial sockets and the 1/2-inch square drive impact adapter.
Closed heavy-duty orange storage case featuring embossed Klein Tools branding for jobsite organization and socket protection.
Electrician using a cordless impact wrench with a Klein 1/2 x 3/8-inch coaxial socket to secure conduit clamp hardware on a jobsite floor.
Technician driving mounting bolts on structural steel framing using a Klein 12-point coaxial socket mounted on a 1/2-inch impact wrench.
Maintenance worker in hardhat using a cordless impact driver fitted with a Klein coaxial socket to service industrial equipment bolts.
Contractor securing overhead structural bracket hardware using a Klein 12-point spring-loaded coaxial socket on an impact wrench.
Electrician using a Klein coaxial 12-point spring-loaded socket on an impact driver to fasten overhead ceiling hardware hands-free.
2-in-1 Impact Socket Sets (Cat. No 66040/66050E) Promotional video
Open compact orange case displaying the Klein 66040 5-piece impact set with four coaxial spring-loaded sockets and a 1/4-inch hex adapter.
Diagram detailing 8 SAE socket sizes in 4 coaxial bodies, 12-point high-torque design, and 1/4-inch hex to 1/2-inch square drive conversion.
Close-up of the Klein 1/4-inch hex shank to 1/2-inch male square drive adapter with spring-loaded retention ball detent.
Four 12-point coaxial sockets and drive adapter lined up to display laser-etched SAE size callouts and color-coded identification bands.
Perspective view of the open orange carrying case organizing four coaxial sockets and the 1/2-inch square drive impact adapter.
Closed heavy-duty orange storage case featuring embossed Klein Tools branding for jobsite organization and socket protection.
Electrician using a cordless impact wrench with a Klein 1/2 x 3/8-inch coaxial socket to secure conduit clamp hardware on a jobsite floor.
Technician driving mounting bolts on structural steel framing using a Klein 12-point coaxial socket mounted on a 1/2-inch impact wrench.
Maintenance worker in hardhat using a cordless impact driver fitted with a Klein coaxial socket to service industrial equipment bolts.
Contractor securing overhead structural bracket hardware using a Klein 12-point spring-loaded coaxial socket on an impact wrench.
Electrician using a Klein coaxial 12-point spring-loaded socket on an impact driver to fasten overhead ceiling hardware hands-free.
2-in-1 Impact Socket Sets (Cat. No 66040/66050E) Promotional video
KLEIN TOOLS

Klein Tools Coaxial Flip Impact Socket Set 66040 5 Piece 8 Sizes (1/2 Square Drive 4140 Steel 12 Point Hardware Installation Kit)

Only 2 left
SKU: 66040
$134.98 USD

Description

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Klein Tools 66040 5-Piece 2-in-1 Coaxial Spring-Loaded 12-Point Impact Socket Set

The Klein Tools 66040 5-Piece 2-in-1 Impact Socket Set delivers eight primary SAE sizes across four coaxial, spring-loaded socket bodies and a 1/4 inch hex to 1/2 inch square drive adapter for fast hardware installation. Forged from high-strength 4140 alloy steel, this 2.3 lb kit complies with ASME B107.2 impact standards and features a 12-point socket geometry that eases alignment onto hex and square fasteners. Designed for electrical utility contractors, commercial electricians, and structural ironworkers, the hands-free spring-loaded socket mechanism lets operators press inner socket sleeves directly over fasteners to instantly switch drive dimensions across eight core sizes ranging from 3/8 inch to 7/8 inch without removing sockets from power tool anvils.

Best Used For:

  • Overhead Utility & Trapeze Bolting: Running strut channel nuts, threaded rod hardware, and utility pole fasteners without stopping to detach or manually flip socket drive bodies.
  • Square & Hex Fastener Installation: Rapidly engaging both 6-point hex bolts and 4-point square hardware using precision-machined 12-point socket profiles.
  • Impact Wrench & Driver Adaptation: Connecting directly to 1/2 inch square drive impact wrenches (such as the Klein BAT20CW1) or converting 1/4 inch power hex impact drivers via the included adapter.

Key Performance & Safety Features

  • Hands-Free Coaxial Spring-Loaded Action: Inner spring-loaded socket automatically retracts when pushed against larger hardware, giving instant 2-in-1 size functionality on single drive heads.
  • 8 Sizes Consolidated in 4 Sockets: Combines 7/8 x 11/16'', 3/4 x 9/16'', 5/8 x 7/16'', and 1/2 x 3/8'' SAE dimensions into four lightweight socket bodies.
  • 12-Point High-Torque Socket Geometry: Provides double the positioning angles of 6-point sockets for easier alignment on both hex and square fastener heads.
  • Forged 4140 Alloy Steel Construction: Heat-treated impact-grade metallurgy meets ASME B107.2 specifications to absorb heavy rotational shock loads.
  • Cross-Hole Pin Retention System: Engineered cross-hole detent lock prevents unintentional separation between the drive adapter and socket bodies under continuous vibration.
  • Color-Coded Visual Identification: Distinctive colored rings permit rapid visual size selection inside dark utility truck bins and jobsite tool bags.

What's Included

  • (1) 7/8-Inch x 11/16-Inch Coaxial Spring-Loaded 12-Point Impact Socket
  • (1) 3/4-Inch x 9/16-Inch Coaxial Spring-Loaded 12-Point Impact Socket
  • (1) 5/8-Inch x 7/16-Inch Coaxial Spring-Loaded 12-Point Impact Socket
  • (1) 1/2-Inch x 3/8-Inch Coaxial Spring-Loaded 12-Point Impact Socket
  • (1) 1/4-Inch Hex Shank to 1/2-Inch Square Drive Impact Adapter
  • (1) Hard-Shell Storage Carrying Case

Technical Specifications

Brand Manufacturer Klein Tools®
Model Part Number OEM SKU 66040
Tool Classification System 5-Piece Coaxial Spring-Loaded 2-in-1 Impact Socket Set
Core Metallurgy Material Forged Heat-Treated 4140 Alloy Steel
Input Drive Interface Sizes 1/2 inch Female Square Drive & 1/4 inch Hex Power Shank Adapter
Socket Size Range (SAE) 7/8 x 11/16'', 3/4 x 9/16'', 5/8 x 7/16'', 1/2 x 3/8''
Socket Point Profile Geometry 12-Point Deep Well Profile
Fastener Safety Retention Cross-Hole Adapter Retention Alignment
Manufacturing Quality Standards ASME B107.2 Compliant
Power Driver Tool Compatibility 1/2 inch Impact Wrenches (BAT20CW1) & 1/4 inch Impact Drivers
Overall Carrying Case Dimensions 5.5 inches L x 4.7 inches W x 1.9 inches H (14.0 x 11.9 x 4.8 cm)
High-Voltage Insulated Frame No (Uninsulated - do not use on energized electrical circuits)
Total Piece Count 5 Pieces (4 Sockets + 1 Adapter + Case)
Assembled Net Package Weight 2.3 lb (1.0 kg)
Global Trade Item Number GTIN 00092644382093

Pro-Tip: When engaging smaller inner hex nuts, push the power impact driver firmly forward. The coaxial outer socket sleeve stays suspended above the work surface while the internal spring-loaded socket seats fully over the fastener head, allowing hands-free size transitions without removing the socket from the anvil.