| Number | Type | Dimensions | PCB thickness | Chip | Pins | Connector | Example |
|---|---|---|---|---|---|---|---|
| 1 | Mattairtech MT-DB-U4 | 52.25 x 22.75mm | 1.6mm | Atmega32U4 | ALL | mini | |
| 2 | Clone Pro Micro New Type | 39.75 x 23.5mm | 1.6mm | Atmega32U4 | 18/20 with hack | mini | Stealth Quark |
| 3 | Clone Pro Micro | 33.5mm x 17.85mm | 1.2mm | Atmega32U4 | 18/20 with hack | micro | Flanck |
| 4 | PJRC Teensy 2.0 | 30.6 x 17.9mm | 1.7mm | Atmega32U4 | 25/26 with hack | mini | Retro Planck |
| 5 | Pololu A-Star Micro | 25.25 x 15.35mm | 1.0mm | Atmega32U4 | 18/20 with hack | micro | Atreus |
| 6 | DF Robot Beetle | 22.4 x 20.4mm | 1.1mm | Atmega32U4 | 10 | micro | |
| 7 | Clone Digispark | 23 x 18mm | 1.6mm | Attiny85 | 6/4 with USB | micro | |
| 8 | Clone Digispark Pro | 27.1 x 18.3mm | 1.6mm | Attiny167 | 13/11 with USB | micro | |
| 9 | PJRC Teensy LC | 35.7 x 17.95mm | 1.6mm | MKL26Z64VFT4 | 27 | micro | Van LC |
| 10 | PJRC Teensy 3.2 | 35.6 x 18.05mm | 1.6mm | MK20DX256VLH7 | 34 | micro | Van 3.2 |
| 11 | STM32F103C8T6 | 53.5 x 22.9mm | 1.2mm | STM32F103C8T6 | 32 | micro | Planck STM32 |
| 12 | Clone Arduino Pro Mini | 32.75 x 17.7mm | 1.6mm | Atmega328P | 20 | none |
Dimensions are measured from the actual boards and do not include the protruding USB connector.
The Pins that are "with hack" require removing existing indicator LEDs and soldering to tiny surface mount pads. On the Teensy 2.0 pin E2 can be accessed by soldering to the tiny pull down resistor.
"with USB" are indicating the loss of 2 pins for use with VUSB, since these board do not have native USB.
The Arduino Pro Mini does not have any USB connector. It can be used with an external VUSB circuit.
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| Top view |
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| Bottom view, some have components on the bottom. |
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| Side view to show relative thickness of boards |
