This adapter cable converts your 2.5 mm TRRS plug terminated cable to a 4.4 mm Pentaconn plug.  Most commonly used for connecting balanced headphones terminated with a 2.5 mm TRRS plug to a 4.4 mm Pentaconn balanced output from an Headphone amplifier, DAP or DAC audio source.  There are many length choices available to double as an extension cable.  This cable transmits a balanced stereo signal.
 
The Pinout is as follows, also pictured above:
 
2.5 mm Tip, R- : 4.4 mm Ring 3
2.5 mm Ring 1, R+ : 4.4 mm Ring 2
2.5 mm Ring 2, L+ : 4.4 mm Tip
2.5 mm Sleeve, L- : 4.4 mm Ring 1
 
All cable options include excellent dielectric insulation and shielding to reject EMI and RFI.
 
OFC Cable Specs
24 AWG Oxygen Free Copper conductors (4x)
High density braided copper shield.
PE dielectric insulation.
PVC Outer Jacket
Outer Cable Diameter:  6.3 mm
 
SPOFC Cable Specs
20 AWG Silver Plated Oxygen Free Copper Conductors (4x)
High density braided copper shield.
PTFE Teflon dielectric insulation
FEP Outer Jacket
Outer Cable Diameter:  5.8 mm
 
OCC Cable Specs
24 AWG Ohno Continuous Cast conductors (4x)
PE Dielectric Insulation
High density braided copper shield.
Aluminum Foil Shield
Double Layer Outer PVC Jacket
Outer Cable Diameter:  8.4 mm
 
Pure Silver Cable Specs
27 AWG Pure Silver conductors (4x)
FEP Inner & PE Outer Layer Dielectric Insulation
High density Silver Plated braided copper shield.
Aluminum Foil Shield
Double Layer Outer PVC Jacket
Outer Cable Diameter:  8.4 mm
 
2.5 mm TRRS Connector Specs
Gold Plated Pure Copper Contacts
Carbon fiber and nonmagnetic stainless steel housing
 
4.4 mm Pentaconn TRRRS Connector Specs
Gold Plated Pure Copper Contacts
Carbon fiber and nonmagnetic stainless steel housing