ThinkPad L series
The L series was developed as a direct successor of the discontinued R series, but it also weirdly made its first debut together with the SL410 and the SL510. Barring the strange naming oddity, the SL410 and the SL510 are exactly identical to the L410 and the L510. The said models were all true successors of the R series, unlike the earlier SL series' IdeaPad-like models which were branched out to its own dedicated series, the E series.
The L series was notable for claiming to be made out of recycled materials, although the claim cannot be properly verified.