Use this corner box on overhangs between 12" Gable x 16" Eave and 18" Gable x 18" Eave @ 4/12 pitch or less.
If Gable is 12" or less and Eave is 16" or less and pitch is 4/12 or less, use TCBM.
If Gable is more than 18" or Eave more than 18" or if pitch is more than 4/12, use TCBXL.
If overhangs are between 12" Gable x 16" Eave and 18" Gable x 18" Eave but pitch is more than 4/12, use TCBXL.