M.2 SSDs can be SATA or PCIe devices. The adapter you'll need depends on which protocol you have. You can usually determine what type it is by the labeling, but it would be best to search for the model number for verification.

PCIe M.2

The drive's label will usually show text similar to "PCIe GenX" or "NVMe".

You will need a PCIe write blocker and an M.2 PCIe Adapter:

W2000 - PCIe Write Blocker - (T7u) - https://digitalintelligence.com/store/products/w2000
A1510 - PCIe M.2 SSD Adapter (TDA7-2) - https://digitalintelligence.com/store/products/a1510

W2455 - PCIe SSD Write Blocker Kit (includes adapters) - https://digitalintelligence.com/store/products/usb-3-1-pcie-write-blocker-kit

SATA M.2

The drive's label will usually have a "Serial ATA" emblem on it and may have the text "SATA".

You will need a SATA write blocker and an M.2 SATA Adapter:

W2710 - SATA UltraBlock - https://digitalintelligence.com/store/products/w2710

A4710 - mSATA and M.2 to SATA Adapter Kit - https://digitalintelligence.com/store/products/a4710
A4720 - mSATA/M.2 SATA SSD Adapter (TDA3-3) - https://digitalintelligence.com/store/products/tda3-3-msata-m-2-sata-ssd-adapter

OPAL Encryption

NVMe SSDs can be encrypted. One of the popular schemes is OPAL, which will have the text OPAL on the label.

Currently, the only write-block devices that can detect OPAL are the TX1 Forensic Imager and TD4 Forensic Duplicator:

TX1
D6280 - https://digitalintelligence.com/store/products/d6280
D6281 - https://digitalintelligence.com/store/products/d6281

TD4
D6300 - https://digitalintelligence.com/store/products/d6300
D6301 - https://digitalintelligence.com/store/products/td4-forensic-duplicator-with-hard-case
D6310 - https://digitalintelligence.com/store/products/td4-forensic-duplicator-with-adapters

Recently there have been new encryption schemes released called Opalite and Pyrite, which are subsets of the OPAL self-encrypting standard. Currently, the TX1 and TD4 do not support these subsets.