Hello,
[2025-10-29 Update] - If you have trouble with the forums/PMs, please feel free to e-mail me directly at drives@nicholasfamilycentral.com
I'll periodically update this first post when stock is low, or I have additional drives coming.
I have ASUS external USB drives on-hand. All have been opened, connected to a Mac & had the drive and firmware verified with MakeMKV. They have a LG drive with firmware that I have flashed to be 4K/UHD compatible, for backing up UHD discs.
Drive details from MakeMKV: 
LibreDrive Information
Drive platform: MT1959
I'm selling the drives for $280 USD, already flashed, new in box (only opened to verify drive Mfg/Model/flash Firmware).
I have many years of experience with LG drives & MakeMKV.  Many experienced MakeMKV users will tell you LG drives are not of the same quality as Pioneer drives.  While I do not disagree, for many years the only drives I personally owned & used were LG.  My slimline drive would not rip maybe 1-2% of my 4K/UHD discs.  My desktop 5 1/4" drive managed the problem discs without any issue.  Between the two drives I have been able to rip 100% of my 4K/UHD collection.  Because of the current public opinion/experience with LG drives vs. Pioneer drives, I am selling these drives for less than the Pioneer drives I also have for sale.  These LG drives are pre-flashed, without any donation or other costs required.
Note:  The drives come with a disc of software that includes various applications & tools.  I have not tested or verified anything on the disc.  I strongly suggest you use caution if you install/use the tools on the disc, especially if any of them may prompt or automatically "update" the drive firmware.  If the drive firmware is modified after being flashed for UHD/4K/backup, the drive may become unflashable or no longer work for UHD/4K/backup!  Please take caution.
Any questions, feel free to send me a PM, e-mail or post in this thread.
Thanks,
Frank