It does depend greatly on how large a system (tank/stand) you are planning on putting on those feet.  I would be very concerned about supporting a heavy (ish) tank/stand on the threads of those feet.  They could possibly warp and possible sheer over time and cause unevenness ?  Furthermore, if the feet are extended I would not think that your tank/stand would be very stable on those 4 thin(ish) bolts. 
		
	
		
		
		
		
			
		
		
		
		
	
		
		
	
	
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