The parts list for your model PC doesn't even show that it comes with a 128 GB M.2 SSD, so what I recommend is to go to the device manager, click on the disk drives device manager category, get the model number of your PC's 128 GB SSD and google it.
It should reveal the type of SSD and the length...It's probably 2280.
Thank you for your reply. I previously checked device manager and it reported a SANDISK SD8MAT-128G-1006 but I have been unable to find any information from HP or SANDISK sites. Just wondered if anyone in the community had any information to save me ripping it open twice lol.
Be alert for scammers posting fake support phone numbers and/or email addresses on the community. If you think you have received a fake HP Support message, please report it to us by clicking on "Flag Post".