You define hook length parameters for a rebar type with the Rebar Hook Length Parameter dialog. Access the dialog by clicking the Hook Lengths Edit button in Rebar Type Properties. See Rebar Type Properties.

Name	Description
Rebar Hook Type	This is a self-populated list of valid rebar hooks for this rebar type. Selecting the check box indicates that the hook type is visible in the Hook at Start or Hook at End parameters of the rebar. See Rebar Instance Properties.
Auto Calculation	Clear this check box to override the automatic calculation of Hook Length and Offset Length.
Hook Length	Displays the length of the hook type.
Offset Length	Displays the offset length of the hook type. Use this optional parameter primarily for scheduling.

The following images depict the parameters that define a rebar hook.

45° Hook