I don't often post in this thread but today I have a recommendation based on significant personal experience.
The subject is Diamond Abrasive Files.
I have used the EZE-LAP brand for decades, however I'm far from satisfied with them. The grit is plated onto a steel sheet metal substrate about .75" x 1.92" and that is glued to a plastic handle. The finer grits (specified as Super Fine, Fine and Medium) are mostly what I used and they were so so to OK. Eventually, the grit will wear off the Medium, Fine and Super Fine files but I wouldn't call them frail. However, the Coarse and Very Coarse grits have performed unsatisfactorily. With substantial hand pressure, the coarser grits rub off the substrate rendering the file useless. I don't often use the coarser grit files but I don't like that they are so frail. One useful aspect of this product is that it's not very difficult to separate the substrate from the handle and use in tight quarters or modify it to a very small dimension as required. I don't think I'll buy any more of this brand/type. Random example of the EZE-LAP product I'm speaking of.
Find many great new & used options and get the best deals for EZE-LAP PAK5 Set SF/F/M/C/XC Color Coded Diamond Hones Sharpening Stones Hand at the best online prices at eBay! Free shipping for many products!
www.ebay.com
I bought the next product a few months ago and I'm impressed with them for many reasons.
It is a six piece set consisting of 80, 240, 400, 800, 1200, and 3000 grits specified. The grit size is marked on each file but my 800 is almost illegible at this point. I will scratch the value onto the plastic base. The grit is plated onto a steel substrate about 20 mm (.787") x 150 mm (5.906"), which is more than three time the area of the EZE-LAP product. Substrate thickness unknown because I haven't had a need to separate one from the full length plastic base. I guess this is not a comprehensive review because I have not used the coarser grits. I suppose the coarsest might be used to dress a grinding wheel. I've mostly used the 800 and been very pleased (surprised actually) with no indication of grit loss or reduction in the 'bite' I feel. I've used the 400, 1200 and 3000 grits only slightly but am perfectly satisfied so far with no sign of problems. Below is the Item I bought.
Diamond sharpening bar Quick sharpening tool Convenient outdoor sharpener Kitchen grinding tool. Material: Diamond. Color: silver.
www.ebay.com
Tonight I will order the more comprehensive set consisting of nineteen different grits.
This is what I intend to buy tonight. When you view the linked item, select the 19 Piece Set from the pull down menu, to see the correct price.
4 DIFFERENT SHARPENING PLATES: There are four different diamond sharpening plates in total for knife sharpener. MORE ACCURATE & EFFECTIVE: This type of sharpening plate can not only be used alone but also used together with the knife sharpener.
www.ebay.com
EDIT: I should add that, IMO, any of the diamond file should be scrubbed periodically with something like Ajax or Comet cleanser to release any retained detritus.