This listing is for one STM32F103C8T6-based development board aka Blue Pill with a couple of convenient tabbed jumpers thrown in. The little grooved handles on the ends of the jumpers make it easier to pull them off the header when switching between boot modes. I would recommend leaving the short jumper on the boot 1 header and using the tabbed jumper on the boot 0 header, since you won't change boot 1 as often as boot 0 and that leaves easy access to the tab on the boot 0 jumper.

Note that the CKS/APM chips are clones and cannot be used with STM32 CubeIDE or STM32 CubeMX, although the ST-Link Utility does work. The clones can still be programmed with other IDEs such as the Arduino IDE or Visual Studio Code. If you want to use STM32 CubeMX or STM32 CubeIDE for all its features including in-circuit debugging then order a Bluepill with a genuine STM chip using the drop-down menu.

Optionally available are the STLink v2 dongle for programming and in-circuit debugging and a specially-assembled 40 cm cable making it less likely to misconnect the STLink to the devboard's programming header. Note that only the STLink-side of the upgraded cable is impossible to insert incorrectly - the devboard-side of the cable must be attached with the label facing up. Colours may vary.

It can be programmed from the Arduino IDE by installing the board definitions from: https://github.com/stm32duino/BoardManagerFiles/raw/main/package_stmicroelectronics_index.json

Specifications:

Operating Voltage: 2.7V to 3.6V

CPU Frequency: 72 MHz

Number of GPIO pins: 35

Number of PWM pins: 12

Analog Input Pins: 10 (12-bit resolution)

I2C Peripherals: 2

SPI Peripherals: 2

CAN 2.0 Peripheral: 1

Timers: 3 (16-bit)

Flash Memory: 64KB + 64KB hidden (requires IDE configuration change in order to access)

RAM: 20kB