It is recommended to keep each office chair unit as a separate FA item, as wear and tear and or even write-off may happen to different unit at different time of the useful life.
 
Example below show 7 different units of executive chair with XXX-1, -2 , -3 ....
 

We recommend to keep it as a separate item in the FA ledger , but you may use category to put them together when you print the report.
 
You are able to print by category and the ram will be added into each computer as a common category