I can't find this part and what is its name?

[vanepp]

From the picture it is a mini360 buck regulator and is available here

Mini-360 DC-DC Buck converter

Mini-360 DC-DC Buck converter available for ebay and other such sources. A tiny ((17mm by 11mm) buck converted module that will do around 2Amps with an adjustable output. All three views present, but pcb not yet verified (I haven’t yet got my set of these ). Mini-360 DC-DC Buck converter.fzpz (15.0 KB) Peter

Peter