21:4(EER-42×15) TRANSFORMER MAKE-HS(HANGSING)

The component in the image is a high-frequency transformer, specifically a ferrite core transformer, commonly used in switch mode power supplies (SMPS), inverters, and power converters.

Here’s a breakdown of the label information:

Label Information:

EER-42X15

This refers to the core shape and size:

EER: Core type — a common ferrite core shape optimized for high-frequency applications.

42X15: Dimensions in mm — 42 mm outer dimension, 15 mm core thickness (approx).

21:4

This indicates the winding ratio:

Likely a primary to secondary winding ratio of 21 turns to 4 turns.

180°C

Maximum temperature rating — the insulation or wire can withstand up to 180°C.

www.hangsing.cn

The manufacturer’s website — Hangsing, a Chinese company known for producing magnetic components like transformers and inductors.
Usage/Application:

Used in high-frequency circuits like:

Switch Mode Power Supplies (SMPS)

DC-DC converters

Inverters

LED drivers
Provides voltage transformation, galvanic isolation, and sometimes impedance matching.
If you’re planning to use it, you’d need to know:

The input and output voltages/currents

Operating frequency (usually in tens to hundreds of kHz)

Mounting style (this one is through-hole)