These spouts will fit all powder flasks, except for small 31 caliber flask. They also fit the 06-23 powder horn valve and our 335M Powder Horn. Spouts are made of solid brass and can be shortened to give the exact charge needed. CAUTION: These measures are to be used with black powder or Pyrodex only. Charge size is approximate only. Black powder and Pyrodex are equivalent by volume only. SAFETY ALERT: Do not load directly from the flask or horn. Always use a separate measure