The YX850 Power Failure Automatic Switching Standby Battery Lithium Battery Module DC5V-48V Emergency Converter. It is an automatic switching module. When the battery is dead or there is a problem with the battery, it is powered by the power supply.
This is Boost Module With Digital Display which is a high-performance step-up switching current module. The XL6009 DC-DC 4.5-32V to 5V-35V XL6009 Boost Step-up Module Adjustable Digital Voltmeter.
The TIP42C is a base island technology PNP power transistor in TO-220 plastic package that make this device suitable for audio, power linear and switching applications. The complementary NPN type is TIP41C.
This is a mini LCD Digital Thermometer for Fridge Freezer, Insert Size 46mm x 26.6mm, Cable Length 1m (Black or White Color) If you open the battery cover to put in two LR44 batteries correctly, pay attention to the polarity.