MIL-DTL-38999 is a high-end military-grade, high-density circular connector available in four series (I, II, III, IV) with full cross-compatibility across domestic and international brands. Series I and II feature bayonet coupling (Series II includes lightweight low-profile shells), while Series III and IV utilize a three-start threaded self-locking mechanism with scoop-proof and anti-misalignment design for blind mating. The complete range offers nine shell sizes from 09# to 25#, including flange receptacles, nut-receptacles, straight plugs, and 90° angled plugs. Multiple shell materials and corrosion-resistant plating options provide salt-spray resistance, impact and vibration durability, and multi-layer sealing against dust, moisture, and oil. Integrated multi-key keying prevents misinsertion, supporting mixed power, high-speed signal, and coaxial configurations for demanding applications in aerospace, defense, new energy, and exploration sectors. D38999/20 (Square Flange Receptacle), D38999/24 (Nut-Locking Receptacle), D38999/26 (Straight Plug) D38999/26WJ09-09PN, D38999/26WJ11-98PN, D38999/26WJ13-35PN, D38999/26WJ15-19PN, D38999/26WJ17-26PN, D38999/26WJ19-32PN, D38999/26WJ21-75PN, D38999/26WJ23-61PN, D38999/26WJ25-98PN D38999/27FJ09-09P, D38999/27FJ13-35P, D38999/27FJ15-19P, D38999/27FJ21-75P D38999/20, D38999/24, D38999/26 D38999/26FJ09-09PN, D38999/26FJ11-98PN, D38999/26FJ13-35PN, D38999/26FJ15-19PN, D38999/26FJ17-26PN, D38999/26FJ19-32PN, D38999/26FJ21-75PN, D38999/26FJ23-61PN, D38999/26FJ25-98PN D38999/30ZF15-19P, D38999/30ZF21-75P, D38999/32ZF15-19S, D38999/32ZF21-75S Superior EMI shielding enables high-speed transmission; scoop-proof structure protects pins; multi-layer sealing ensures weather and durability; contacts are crimp-removable for easy maintenance; high-strength shells resist shock and vibration; mixed pin arrangements supported; IP67 protection rating; multiple plating options for various salt-spray environments. Connection Types: Series I/II Bayonet Lock, Series III/IV Three-Start Threaded Self-Lock Pin Counts: 3~128 pins, compatible with #12/#16/#20/#2 2D contacts Operating Temperature: -65℃ to +175℃ (Stainless steel models up to 200℃) Key Features: Multi-key anti-misinsertion, EMI shielding, Scoop-proof structure