Electric Blue Lobsters are generally P. alleni or Cherax quads (occassionally it'll be P. clarkii). P. alleni is a bit more expensive to get your hands on than quads (places like crazycrays.com sell quads 3 for $15), and it's more aggressive towards tank mates. But uh, they're crayfish not lobsters. The use of lobster in the name is generally so stores can get around laws that would prohibit their sales (not always, but common enough... happens a lot in TX & WA with species in the cherax genus because they're restricted species), sometimes it's just the common name though (but that's not helpful either because they'll overlap with other species' names).