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Description
Adafruit Feather M4 Express - Featuring ATSAMD51 Cortex M4#3857 It's what you've been waiting for, the Feather M4 Express featuring ATSAMD51. This Feather is fast like a swift, smart like an owl, strong like a ox bird (it's half ox, half bird, OK?) This feather is powered by our new favorite chip, the ATSAMD51J19 with its 120MHz Cortex M4 with floating point support and 512KB Flash and 192KB RAM. Your code will zig and zag and zoom, and with a bunch of extra peripherals for support, this will for sure be
#3857
It's what you've been waiting for, the Feather M4 Express featuring ATSAMD51. This Feather is fast like a swift, smart like an owl, strong like a ox-bird (it's half ox, half bird, OK?) This feather is powered by our new favorite chip, the ATSAMD51J19 - with its 120MHz Cortex M4 with floating point support and 512KB Flash and 192KB RAM. Your code will zig and zag and zoom, and with a bunch of extra peripherals for support, this will for sure be your favorite new chipset.
And best of all, it's a Feather - so you know it will work with all our FeatherWings! What a great way to quickly get up and running.
The most exciting part of the Feather M4 is that while you can use it with the Arduino IDE - and it's bonkers fast when you do, we are shipping it with CircuitPython on board. When you plug it in, it will show up as a very small disk drive with main.py on it. Edit main.py with your favorite text editor to build your project using Python, the most popular programming language. No installs, IDE or compiler needed, so you can use it on any computer, even ChromeBooks or computers you can't install software on. When you're done, unplug the Feather and your code will go with you.
Here are some of the updates you can look forward to when using Feather M4:
- Measures 2.0" x 0.9" x 0.28" (51mm x 23mm x 8mm) without headers soldered in
- Light as a (large?) feather - 5 grams
- ATSAMD51 32-bit Cortex M4 core running at 120 MHz, 32-bit, 3.3V logic and power
- Hardware DSP and floating point support
- 512 KB flash, 192 KB RAM
- 2 MB SPI FLASH chip for storing files and CircuitPython code storage.
- No EEPROM
- 32.768 KHz crystal for clock generation & RTC
- 3.3V regulator with 500mA peak current output
- USB native support, comes with USB bootloader and serial port debugging
- Built in crypto engines with AES (256 bit), true RNG, Pubkey controller
- Tons of GPIO! 21 x GPIO pins with following capabilities:
- Dual 1 MSPS 12 bit true analog DAC (A0 and A1) - can be used to play 12-bit stereo audio clips
- Dual 1 MSPS 12 bit ADC (6 analog pins some on ADC1 and some on ADC2)
- 6 x hardware SERCOM - Native hardware SPI, I2C and Serial all available
- 16 x PWM outputs - for servos, LEDs, etc
- I2S input and output
- 8-bit Parallel capture controller (for camera/video in)
- Built in 100mA lipoly charger with charging status indicator LED
- Pin #13 red LED for general purpose blinking
- Power/enable pin
- 4 mounting holes
- Reset button
The Feather M4 Express uses the extra space left over to add a Mini NeoPixel, 2 MB SPI Flash storage and a little prototyping space. You can use the SPI Flash storage like a very tiny hard drive. When used in CircuitPython, the 2 MB flash acts as storage for all your scripts, libraries and files. When used in Arduino, you can read/write files to it, like a little datalogger or SD card, and then with our helper program, access the files over USB.
Easy reprogramming: the Feather M4 comes pre-loaded with the UF2 bootloader, which looks like a USB storage key. Simply drag firmware on to program, no special tools or drivers needed! It can be used to load up CircuitPython or Arduino IDE (it is bossa-compatible)
Comes fully assembled and tested, with the UF2 USB bootloader. We also toss in some headers so you can solder it in and plug into a solderless breadboard.
Lipoly battery and USB cable not included (but we do have lots of options in the shop if you'd like!)
Features
- Product Dimensions: 51.0mm x 22.8mm x 7.0mm
- Product Weight: 4.8g
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.2 ★★★★★
Based on 23 reviews
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Product Reviews
★★★★★ 5
Must have
These things a freaking AWESOME!
If you're doing a big sound deadner job, you need thees! The 3 different sizes are perfect for the different shapes in the floor pans. Well built, good quality and they have a nice weight to them. Just buy them and thank me later. For $15.00 you can't go wrong.
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Reviewed in the United States on March 12, 2026
★★★★★ 5
Bringing a 1976 MG Midget to the modern world!
Material Type: 157mil Closed Cell Foam, Style: 157 mil 36 SqFt
I've been restoring a 1976 MG Midget barn find. I bought some Sinless liner to help make the car rattle less and feel more solid.
This product is easy to cut, easy to install, and extremely sticky. I used it to line the trunk, the interior, and even some under the hood of the old MG. The adhesive stands up to the brutal temperature of the engine bay, and when (by accident) some fuel spilled onto the foam, it didn't fall apart or turn to mush.
Thanks to Siless, the MG now feels like a modern car. The floor pans feel much more solid, the doors make a heftier thud when you close them, and the trunk no longer sounds like a percussion instrument when you touch it.
If you know what you're doing, this product will transform the feel of a car. I found that 36 sq ft was enough for my MG Midget, but for a bigger car I would want more. The pattern on the back helped me to cut perfectly measured squares and rectangles. The foam itself doesn't have a strong odor, it works super well, and has held up to several months of changing temperatures (in the Midwest US.)
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Reviewed in the United States on November 11, 2025
★★★★★ 5
Excellent Car Sound Deadening and Heat Insulation Solution
Material Type: 157mil Closed Cell Foam, Style: 157 mil 36 SqFt
If you're looking for a high-quality car sound deadening and heat insulation material, then the Siless Liner 157 (4 mm) mil 36 sqft is definitely worth considering. This product is designed to offer superior noise reduction and heat insulation for your car, making your driving experience more comfortable and enjoyable.
The closed-cell foam material used in this product is of premium quality, and it effectively blocks out external noise and vibrations. This means you can enjoy a quieter and more peaceful ride, even on noisy roads. In addition, the Siless Liner 157 also provides excellent heat insulation, which can help keep your car cooler in hot weather.
One of the best things about this product is that it's very easy to install. You don't need any special tools or equipment, and the material can be easily cut to fit any shape or size. It's also very lightweight and flexible, which makes it easy to work with.
Overall, the Siless Liner 157 (4 mm) mil 36 sqft Car Sound Deadening Closed Cell Foam & Heat Insulation mat is an excellent choice for anyone looking to improve the comfort and performance of their car. It's a high-quality product that delivers on its promises, and it's definitely worth the investment.
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Reviewed in the United States on March 12, 2023
★★★★★ 4
Heavy-Duty That Works!
Material Type: 157mil Closed Cell Foam, Style: 157 mil 36 SqFt
This extreme sound deadening mat performs well for reducing road noise and vibration. It feels dense and adheres securely when properly applied. Once installed, it noticeably improves interior quietness.
Overall, it’s a strong choice for more serious sound insulation projects.
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Reviewed in the United States on May 12, 2026
★★★★★ 5
Good product, quite sticky I must say.
Material Type: 157mil Closed Cell Foam, Style: 157 mil 36 SqFt
Worked for my van insulation
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Reviewed in the United States on June 1, 2026