select
  unique b.session_recid session_key,      -- SESSION_KEY NUMBER
  b.session_recid,                         -- SESSION_RECID NUMBER
  b.session_stamp,                         -- SESSION_STAMP NUMBER
  b.recid bs_key,                          -- BS_KEY NUMBER
  a.set_stamp,                             -- SET_STAMP NUMBER
  b.set_count,                             -- SET_COUNT NUMBER
  modification_time,                       -- MODIFICATION_TIME DATE
  a.bytes,                                 -- FILESIZE NUMBER
  sys.dbms_rcvman.num2displaysize(a.bytes) filesize_display -- FILESIZE_DISPLAY VARCHAR2(4000)
from
  v$backup_spfile a,
  v$backup_set_details b
where
  a.set_stamp = b.set_stamp and a.set_count = b.set_count