Difference Between Take Off and Starting Collar - Which One Should I Use?
Start collars and take offs are terminology that are used interchangeably.  Finger type ( fold over tabs) are generally used in duct board plenum and trunk lines.  Collar types are used with sheet metal distribution systems.  Sheet metal uses three short metal screws in each collar with mastic or other sealing products.  The finger type collar has flexible duct attached with a first layer duct tape, attaching the inner liner to the collar.  Next is a coating of mastic over the tape completely.  Pull the flexible insulation and vapor barrier over the joint and secure with a large nylon zip tie.  Trim the zip tie and you are done.