Question 1

Are these OEM or refills?

Accepted Answer

Yes these are OEM, original new units.  They're the "high" capacity toner cartridges.  To get the most out of the cartridge, you can reset the counter on your printer.  (Keep track of when you do this in a spreadsheet - I've found I can get 8-10,000 copies if I reset 2 times when it shows about 20% used. 
I have two, MFC-9970CDW's.  Other machines should have similar procedures.
To reset the cartridge:
1. Open the front "door" that gives access to the cartridges
2. pull out the cartridges tray
3. push the cartridge tray back in
4. close the "door" and immediately open it
5. press "1" on the keypad
6. a reset menu will appear, scroll down to the cartridge you want to reset Y.TNR-S.HC would be the yellow, high capacity cartridge, K.TNR-S.HC would be the black cartridge, M=magenta, C=cyan. 
7. Select the cartridge to reset, and accept.
8. The display will say "Accepted"
9. Close front cover
10.  Printer will go through its warm-up/boot cycle and will now indicate the cartridge as being "full".

For other printers reset procedure, either call Brother support or search on-line.  I got my instructions from Brother.

Question 2

since normal office supply store sell this for more than $100, please verify that this is an original Brother product and not some compatible product?

Accepted Answer

As far as I can tell these are genuine Brother cartridges.  I have had then in the printer for a few months now and have had no issues.   Had to make sure to tell the printer that it was a high yield cartridge so the usage indication will be accurate.

Brand	Brother
Model	TN315BK

Cartridge Quantity	Single Pack
Cartridge Color	Black
Compatible Products	HL-4150CDN, HL-4570CDW, HL-4570CDWT, MFC-9460CDN, MFC-9560CDW, MFC-9970CDW
Approximate Page Yield	6000 Pages
Coverage	5%

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