D38999 Part Number Decoder & Specification Tool
This D38999 part number decoder allows engineers to quickly interpret MIL-DTL-38999 connector codes, including shell size, insert arrangement, contact type, and keyway orientation. MIL-DTL-38999 circular connectors are widely used in aerospace, defence and harsh environment applications. Type any D38999 Series III or Series IV part number into the field below for an instant breakdown of every element and mating halves. Or, if you are specifying a connector from scratch, use the 'Build Part Number' button to step through your requirements interactively and arrive at the correct part number for your application in seconds.
You can also use our Cable Bundle Calculator to estimate harness bundle diameter alongside connector selection.
Start typing a part number below, or click Build Part Number to begin your specification.
Shell Style
Shell Size
Contact Type
Series
Material
& Finish
Insert Arrangement
Keying Position
Enter a D38999 part number above to decode it.
Bill of Materials
Part Number
Qty
MIL-DTL-38999 Connector Specification Tool
Most D38999 connector part number tools stop at decoding. This one goes further. Whether you are verifying an existing part number, specifying a new connector for a harness design, or looking up the correct tooling and contacts at the point of assembly, everything you need is in one place - no datasheets, no spreadsheets, no cross-referencing.
How to Read a MIL-DTL-38999 Part Number
Every MIL-DTL-38999 connector part number encodes a precise and complete connector specification. Type any D38999 Series III or Series IV part number into the decoder and get an instant breakdown of every segment:
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Shell Type - mounting style, coupling mechanism, plug or receptacle, series and durability rating.
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Shell Finish - plating material, corrosion resistance, operating temperature range and RoHS compliance status.
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Insert Arrangement - contact arrangement code, total contact count, available contact sizes, wire gauge ranges, and service rating including operating voltages and dielectric withstanding voltages at altitude.
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Contacts - part numbers for each contact size in the arrangement, wire gauge compatibility, test current rating, voltage drop specification, and filler plug part numbers and colour codes.
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Tooling - crimp tool, turret, insertion tool and extraction tool part numbers for each contact size, grouped where the same tool covers multiple sizes.
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Keyway Orientation - polarisation code and keyway positions, with a visual diagram showing keyway locations as viewed from the mating face.
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Mating Halves - automatically generated part numbers for all compatible mating connectors in the same series, with the most commonly specified options highlighted.
D38999 Connector Part Number Breakdown Example
D38999/26FJ35PN
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D38999 – Specification standard
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26 – Shell style
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F – Finish / plating
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J35 – Insert arrangement
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P – Pin contacts
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N – Keyway orientation
Specifying a D38999 Connector with the Part Number Builder
Selecting the right D38999 connector part number for a new design has traditionally meant working through multiple datasheet tables - cross-referencing shell types, insert arrangements, contact sizes, wire gauges and finish codes before arriving at a valid part number. Errors at this stage can result in incorrect tooling being specified, or incompatible mating halves being ordered.
The D38999 Part Number Builder eliminates this process entirely. Rather than starting with a part number and working backwards, the builder starts with your application requirements and works forwards - guiding you through each decision in the correct order, filtering available options based on your previous selections, and ensuring that only valid, compatible combinations are presented at every step.
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Series - Select Series III triple start thread or Series IV breach lock based on your coupling requirement and mating cycle needs.
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Shell Type - Select your mounting style and whether you need a plug or receptacle, filtered to your chosen series.
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Shell Finish - Select the plating finish based on material compatibility, corrosion resistance and operating temperature requirements, with RoHS status shown for every option.
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Wire Gauges - Enter the number of conductors you need at each wire gauge from 28 AWG down to 8 AWG. The builder instantly filters available insert arrangements to show only those that can accommodate your exact wiring requirements, correctly handling overlapping wire gauge to contact size compatibility, and updates in real time as you refine your inputs. This turns what was previously a multi-table manual exercise into a matter of seconds.
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Contact Style - Select pin or socket contacts and your required durability rating.
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Keyway Orientation - Select your polarisation code, filtered to your shell size.
Your completed part number is entered into the decoder automatically, giving you the full specification breakdown ready to transfer to your engineering drawing or bill of materials.
Who Uses This Tool?
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Design Engineers specifying D38999 connectors for new harness designs, verifying insert arrangements against wiring requirements, or checking contact current ratings against load calculations.
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Procurement and Supply Chain Teams identifying connector specifications from a part number on a bill of materials, generating mating half part numbers, or verifying proposed substitutes against original specifications.
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Harness Technicians and Assemblers looking up crimp tools, insertion and extraction tools, and filler plug part numbers at the point of assembly without consulting separate tooling catalogues.
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Quality and Inspection Teams verifying that connector part numbers, tooling and contacts on a build standard or inspection record match the required specification.