A few months ago, I ordered (and reviewed) a set of SUNLOY 8GB uSD cards, and they were great. I ordered these 16GB cards expecting a similar experience, but not quite...The packaging is identical, with the same ambiguity about how many cards are actually present. The product page adds to the confusion with the "4 Pack" graphic tag, but it was clear enough to me that this was a "2 Pack", even though the packaging implies only one card.When I benchmarked the first card, the performance was consistently good. The advertised read rate is 80MB/s, and I was seeing 89MB/s, which is close to what I saw on the 8GB cards. The write rate is less impressive, but not terrible (mostly steady around 28MB/s).When I got to the second card, things were a bit different. The read rate was an inconsistent "stair case", declining from 47MB/s down to 24MB/s, and the write rate was between 30MB/s and 7MB/s.The second benchmark run on the second card was more consistent, with a read rate of about 23MB/s, and a write rate averaging 17MB/s. Clearly something is wrong with the second card. I also noticed that my computer did not automatically mount the second card, so it may either have been badly formatted, or reported an error for some other reason. Sure enough, gparted shows the filesystem as "unknown", so there is a partition present, but it seems to be corrupt.I decided to image the good card onto the bad one, which would serve the dual purpose of validating a write of the complete card, and leaving the card with a valid vfat filesystem on it. The re-imaging seemed to go okay, because I did not see any error messages in the log, and I did properly flush the write buffer before ejecting the media, but when I tried mounting the media again, I ran into problems. This card has problems and does not appear to be usable. Into the trash it goes...So one out of two ain't bad, but it ain't good either. Two stars this time.[40020.373609] usb 8-1.4.2.1: SerialNumber: 000000001617[40020.374717] usb-storage 8-1.4.2.1:1.0: USB Mass Storage device detected[40020.374994] scsi host1: usb-storage 8-1.4.2.1:1.0[40021.414091] scsi 1:0:0:0: Direct-Access Generic MassStorageClass 1617 PQ: 0 ANSI: 6[40021.414522] sd 1:0:0:0: Attached scsi generic sg1 type 0[40021.824826] sd 1:0:0:0: [sdb] Spinning up disk...[40022.882208] .........[40042.873672] sd 1:0:0:0: [sdb] Media removed, stopped polling[40042.874208] sd 1:0:0:0: [sdb] Attached SCSI removable diskGParted 1.5.0configuration --enable-libparted-dmraid --enable-online-resizelibparted 3.6Error opening /dev/sdb: No medium found--Pre-post update:I was just about to post this review, and I figured I'd rule out the uSD-to-SD adapter that came with the second card. I put the uSD into a name-brand adapter and then the second uSD card worked perfectly. I closely inspected the included adapter, but I could not see anything wrong with it visually. To confirm that the issue was the adapter, I tried the second uSD card in its original adapter again, and now it works fine there as well. Note: I did plug, and un-plug the second card into my reader multiple times before switching adapters, and it consistently failed. I don't really know what to make of this, but now the second card appears to be just fine, although I did notice that it's a bit warmer than expected after use.Into the "suspect" pile it goes...Three stars now.