High Level Cut
Gloves offering High Levels of Cut Resistance would have had a 4 or 5 showing for cut resistance, these gloves are being re-tested and you will see the 4 or 5 change to X, a letter will be at the end instead, ranging from A to F.
As new stock comes in and feeds through, you will find your usual gloves with a letter C, D, E or F on them, the vast majority of gloves will still be the same glove, just a different cut test done to assess it's suitability.
If your job demands a high level cut resistant glove with protection up to level 5, to protect your hands you will probably have been buying CUT 5 safety gloves. The cut level for gloves has even higher levels of cut resistance with E and F level gloves.