20 pcs AMS1117 3.3V 1A Voltage Regulator AMS1117-3.3V

It's all it claims to be. I use these to supply 3.3v to esp8266 modules from the 5v I feed led panels, and it makes the boards compact and cheap: one of these, a commodity resistor and pair of capacitors, and you've got a stable 3.3v power supply.

Good price for a great (must have) product.