In 2006 I bought a battery-Schlagschrauberset of Ryobi and have since impressed by the brand. Allow the Ni-Cd batteries to after 8 years of use now slowly, self-discharge occurs. Did I buy the BPL1815 with charger and RB18L40. The new lithium batteries I am happy top. Lighter weight, at least same performance with very short loading times. The 4Ah battery I have not got empty during the work! Because it really does not interest me if the new batteries fit visually to the "old" blue tools.