128GB is currently at its lowest price according to 3xCamel. The 256GB isn't far off it's cheapest price. These USB's are getting on in age but represent substantial value for what you get.
Common complaints are that the USB can retract back into its shell is tight ports, so holding the slider on the side maybe required on insertion. These drives also run hotter than your standard plastic drives. I agree with the comments below, but also have not faced any issues yet with the heat yet.
*Designed specifically for next-generation devices with the new USB Type-C port. The reversible connector has a symmetric design, so that it’s always right-side up, making it easy and fast to plug in.
*High-speed (lol) USB 3.1 performance of up to 150MB/s means you spend less time waiting to transfer your photos, videos, songs, and other files between devices.
*With dual connectors, the SanDisk Ultra Dual Drive USB Type-C lets you free up space on your smartphone or tablet, or transfer files between multiple devices, whether it has a USB Type-C port or the traditional USB Type-A port.
SanDisk Memory Zone app for file management available from the Google Play™ store. The App lets you view, access, and back up all the files from your phone's memory in one location. It can also automatically move files from your device to your drive to free up space.
I have the 64GB model and it gets really hot when plugged in even when not accessing data.