Genuine silver OEM YAMAHA rear shock spring. The black mark signifies a 4.9kg/mm or K=49N/mm spring rate. 

This colour code was used as a standard spring on YZ 125 and 250 2003 - 2013 

Believed to be compatible with most Yamaha YZ125/YZ250 models from approx late 1990’s onwards. 

This spring has had very little use, and stored for a number of years. 

No signs of damage. See other auctions for similar springs with different ratings