The components of activator are all except:
COMPONENTS OF THE ACTIVATOR
It consists of the following elements:

Labial bow: The wire used is spring hardened 0.9 mm stainless steel. The primary wire element of the activator consists of an upper and/or lower labial bow. It consist of horizontal middle sections, two vertical loops and wire extensions through the canine-deciduous first molar embrasure into the acrylic body.
Jack screw:  Optional (fitted to maxillary arch).
Acrylic portion: This can be fabricated in cold cure acrylic directly on the models or a wax matrix can be made first and then invested in the flask.

Key Concept: 
Delta Clasp is used in Twin Block appliance.
Reference: Textbook of orthodontics 2nd ed Gurkeerat Singh page no 519
Labial bow
Jack screw
Acrylic portion
Delta clasp