Since 2008, the Saitama Seibu Lions have had a handful of games each year dubbed "Lions Classic" games, where the team wears "Turn-Back-The-Clock" uniforms. Each season has featured a different era - 2008 was the 1950's Nishitestsu Lions, 2009 was the 1980's Seibu Lions, 2010 was the 1970's Taiheiyo Club Lions and 2011 was the 1951 Nishitetsu Lions. BBM issued small box sets in 2008 and 2009 featuring cards of OB players from the featured era along with cards of the active players wearing the retro uniforms. BBM included a subset in the Lions 60th Anniversary set for the 2010 Lions Classic games.
For 2011, BBM decided to create a whole new 99 card set celebrating all four years of Lions Classic games. The set has eight different subsets - one subset including OB players from the featured era from each of the four seasons and one subset including active players wearing retro uniforms from each of the four seasons. There are 9 active and 9 OB cards for the 2011 Classic, 9 active and 9 OB cards for the 2010 Classic, 12 active and 15 OB cards for the 2009 Classic and 12 active and 12 OB cards for the 2008 Classic. There's also a 12 card subset featuring an active and an OB player.
As you might expect from a set with 42 cards of active players from the past four seasons, several players have multiple cards. Takumi Kuriyama, Hiroyuki Nakajima, Takeya Nakamura and Hideaki Wakui appear in all four active subsets as well as the 12 card combination subset. Many other players (including some of the OB players) appear in multiple subsets as well.
I like the fact that some of the OB players (like Yasuhiro Fukami and Takeshi Hibino) have not previous appeared in any of the recent Lions OB sets. I don't like the fact that the photos on the combination subset cards are the same as the photos in the rest of the set - maybe BBM has done so many Lions OB sets recently that they've run out of photos.
Here's some sample cards (as always, you can see all of them here):