  Anomalous X-ray Pulsars and Soft-Gamma Repeaters groups are magnetar
candidates featuring low characteristic ages ($\tau = {P\over{2 {\dot P}}}$).
At least some of them they should still be associated with the remnants of the
explosive events in which they were born, giving clues to the type of events
leading to their birth and the physics behind the apparent high value of the
magnetar magnetic fields. To explain the high values of $B$, a self-consistent
picture of field growth also suggests that energy injection into the SNR is
large and unavoidable, in contrast with the evolution of {\it conventional}
SNR. This modified dynamics, in turn, has important implications for the
proposed associations. We show that this scenario yields low ages for the new
candidates CXOU J171405.7-381031/CTB 37B and XMMU J173203.3-344518/G353.6-0.7,
and predicted values agree with recently found ${\dot P}$, giving support to
the overall picture.
