Shimano di2 bcr2 charger for btr2di2 charger for the internal battery that will keep your di2 system shifting featuresdi2 uses a powerful long life 74v li ion battery keep it in top condition and ready for shifting with this specific shimano di2 charger15 hour charge timeplugs in directly to the sm ew90 handlebar junction acan also be used for completing firmware updates when linked to e tube software on your pca 2 year warranty is offered with all shimano products from chain reaction cycles