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Gecko Connectors

1.25mm Pitch High-Reliability Connectors

Harwin’s Gecko (G125 series) connectors provide a low profile, dual row interconnect solution, ideally suited for stacking and cable mating in areas where PCB real estate is at a premium. Vibration and shock resistant, miniature yet powerful.

About Gecko

  • 2A per contact (all electrically loaded; 2.8A per individual contact)
  • 4-finger Patented* contact design to maintain electrical contact through high vibration and shock
  • Beryllium Copper contact for improved temperature range: -65°C to +150°C
  • 1,000 mating cycles durability
  • Weight and space saving over Micro-D connector products
  • Future-proofed materials – halogen-free, PFOS-free, SVHC-free and RoHS compliant
  • Low outgassing properties – 0.68% TML, 0.01% CVCM, 0.26 WVR (Water Vapour Recovered)

Product Styles

  • Gecko-SL (Gecko Screw-Lok) – The jackscrew connector range, built with easy and fast “Mate-before-Lok” screw fixings. Connectors are fully mated before the captive screws need to be engaged. The range also features Metal Backshells, giving the option of shielded cable assemblies when used with external braiding.
  • Gecko with Latches – The original Gecko range features latching mechanisms on the Male connectors, easy to release either by hand or with the Harwin-designed unlatching tools. This option gives the maximum amount of space saving footprint.

See also Gecko-MT – Developing the Gecko-SL range to include power contacts capable of 10A max. Available in 1 power / 8 signal / 1 power configuration, or 2 power / 8 signal / 2 power configuration. Also compatible with existing Metal Backshells.

Size/Weight Advantage

With space and weight a consideration for many high-reliability applications, Gecko delivers a pin spacing of 1.25mm, up to 50 contacts per connector. This design means that G125 connectors achieve up to 45% space saving, up to 75% weight saving over other high-performance connectors such as Micro-D.

16-contact Gecko Screw-Lok (dark grey) overlaid with 15-contact Micro-D (light grey)
26-contact Gecko with Latches (dark grey) overlaid with 25-contact Micro-D (light grey)

Gecko is a focus product for Harwin, and is undergoing an active development program. The connectors are designed with automated assembly systems in mind – all connectors can be purchased in Tape and Reel packaging.

* Patent Status: Granted US9017089, GB2501063, GB2548777

Technical Details


Female Contacts

High performance Beryllium Copper, Gold finish

Male Contacts

Copper Alloy, Gold finish


30% Glass-Filled High Temperature Nylon (Polyamide) 4T, rated to UL94V-0


Stainless Steel


Copper Nickel Tin alloy, Tin over Nickel finish


PTFE Equipment wire

Potting Compound

Stycast 2651MM with Catalyst 9



2.8A max per individual contact, 2A max all contacts electrically loaded

Working Voltage

450V DC or AC peak (250V DC or AC peak at 70,000ft/21km/44mbar)

Maximum Voltage

600V DC or AC peak (350V DC or AC peak at 70,000ft/21km/44mbar)

Contact Resistance

25mΩ max

Insulation Resistance

1GΩ min


Operating Temperature

-65°C to +150°C

Humidity Classification

56 days at 93% RH

Vibration (with latches)

10-2,000Hz, 1.5mm, 198m/s² (20G), 6 hours total

Shock (with latches)

981m/s² (100G) in Z Axis, 490m/s² (50G) in X & Y Axis


0.68% TML, 0.01% CVCM,
0.26 WVR (Water Vapour Recovered)


Durability (contacts)

1,000 mating cycles

Durability (latches)

100 mating cycles

Insertion force (per contact)

2.8N max

Withdrawal Force (per contact)

0.2N min

Latch retention force (per mating pair)

20N min

Wire Specification

Recommended Wire types

BS 3G 210 Type A, MIL-W-16878/6 type ET or NEMA HP3 type ET

Wire Sizes

26 to 32 AWG

Insulation Diameter

Ø0.80mm max

Strip Length

1.50 – 1.75mm


Technical Documents

Component Specification (including pin numbering system)

PDF Download

Catalog & Brochures

Gecko-SL – Product Summary brochure

PDF Download

Gecko-SL Metal Backshells – Product Summary brochure

PDF Download

Gecko Flex Circuit Assemblies – Product Summary brochure

PDF Download

Gecko – complete Catalog section

PDF Download

Test Reports

Test Report HT030 – Gecko (G125 Series) – Electrical, Mechanical and Environmental

PDF Download

Test Report HT067 – Gecko-SL – Mechanical

PDF Download

Test Report HT069 – Gecko – Backpotting Temperature Test

PDF Download

Test Report HT073 – Gecko-SL Horizontal – Electrical, Mechanical and Environmental

PDF Download

Test Report HT074 – Gecko Flex Circuit – Electrical

PDF Download

Test Report HT075 – Gecko-SL Shielded Cable Assemblies

PDF Download

Product Training


PDF Download

Gecko with Latches

PDF Download

Panel Mount with Gecko-SL

PDF Download

Flex Circuit Assemblies with Hi-Rel Connectors

PDF Download

Browse the Range

Cable Assemblies

Ready-to-use cabled connectors, single or double ended, fully inspected and tested. Backpotted for added strain relief. Ideal for both prototyping…

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Cable Connector Parts

Cable housings and contacts, sold separately. Pre-wired contacts available for prototyping and full production. See Accessories and Tooling for cable…

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PCB Connectors

Board-mounted connectors, Surface Mount or Throughboard. Low profile, with a variety of screw-lok or latching options.

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Tooling & Accessories

Associated products and tooling for the Gecko range.

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