China's Permalloy grade is 1JXX, where J means "precision alloy", "1" means soft magnetic, followed by a number for the serial number, usually indicates the nickel content of the alloy. For example, 1J50, 1J851 and so on. Perm alloy has high permeability, so it is often used in the core of medium and high frequency transformers or devices with strict requirements for sensitivity, such as high frequency (tens of kHz) switching power transformers, precision transformers, leakage switching inductors, magnetic shielding, yokes and so on.
