To find out if this is the right model of STI gear lever, please roll back the original hood from the handlebars.

Roughly where the handlebar clamp band is, on the outside of the main plastic housing on the right hand lever, there is a molding. This is where you will find the model number.

Link to Shimano's tech page on these levers: http://si.shimano.com/php/download.php?file=pdf/ev/EV-ST-5600-2441A.pdf 

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