Standard Z-cap is an axial-type capacitor made from metallized polypropylene, specifically manufactured for audio application.
The materials uses are chosen for best possible sonic results in its price range.
Even standard caps are made to provide lowest possibly microphonic effect.
The capacitors are available in a wide range of capacitance values with low tolerance, +/- 5%.
The finish is a flame-retardant tape wrap.

Technical data:

AC value of the voltage rating: 400 VDC/200 VAC
Dielectric: Polypropylene
Tolerance: max. 5%, typically 3%
Loss ang. tan = 0.0002 for 1kHz /1uF