Sparklers are hand-held fireworks that burn slowly while emitting sparks.

 

Typical redox-reactions taking place during ignation include:

10 Al + 3 Ba (NO₃)₂ → 3 BaO + 3 N₂ + 5 Al₂O₃
15 Fe + 4 Ba (NO₃)₂ → 4 BaO + 4 N₂ + 5 Fe₃O₄

3 Fe (s) + 2 O₂ (g) → Fe₃O₄ (s)

You should not burn a sparkler indoors because part of the nitrate nitrogen is not completely reduced to the oxidation stage zero, but released as nitrogen dioxide:

2 Al + 3 Ba (NO₃)₂ → 3 BaO + 6 NO₂ (g) + Al₂O₃

 

Reference

• Chemie der Wunderkerze – ein Thema nicht nur in der Weihnachtszeit,
  Christina Martin, Tönjes de Vries,
  Chemkon 2014, 11 (1), 13–20.
  https:doi.org/10.1002/ckon.200410002