This part is a kind of semiconductor called STF0402.

Function of this product has COMMON MODE CHOKE.

Manufacturers : Superworld Electronics

Image and pinout :

Some of the text within the PDF file :

COMMON MODE CHOKE 1. PART NO. EXPRESSION : STF0402 SERIES STF0402100YZF (a) (b) (c) (d)(e)(f) (a) Series code (b) Dimension code (c) Inductance code : 100 = 10.0uH (d) Tolerance code : Y = ±40% (e) X, Y, Z : Standard part (f) F : Lead Free 2. CONFIGURATION & DIMENSIONS : A 4 3 100Y H 1 W B G C E F 2 I PCB Pattern Unit:m/m A 4.60±0.3 B 5.00±0.3 C 2.50±0.3 E 3.00±0.3 F 4.60±0.3 G 3.40 Ref. H 0.80 Ref. I 1.20 Ref. I W 0.50±0.1 3. SCHEMATIC : 1 2 N1 N2 3 4 " " : Polarity NOTE : Specifications subject to change without notice. Please check our website for latest information. 09.05.2008 SUPERWORLD ELECTRONICS (S) PTE LTD PG. 1 COMMON MODE CHOKE 4. MATERIALS : e e c b (a) Core : Ferrite Core (b) Wire : Enamelled Copper Wire (c) Base : Phenolic (d) Adhesive : Epox [ ... ]

STF0402 PDF Datasheet Download