This adapter cable is terminated with a 4.4 mm Pentaconn jack and a 2.5 mm TRRS Plug.  It will allow you to connect your balanced headphones & IEMs with 4.4 mm Pentaconn terminations into DAP's, DAC's and amplifiers with 2.5 mm TRRS outputs.  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.
 
This Cable is available in OFC, SPOFC, OCC & Pure Silver. 
 
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 Connector Specs
Gold Plated Pure Copper Contacts
Carbon fiber and nonmagnetic stainless steel housing