Actuable downhole tools for attachment to tubular strings

A downhole tool for attachment to a tubular string and configured to receive a milling tool that includes a cutting diameter DM, the downhole tool comprising:

• a tubular mandrel configured for attachment to the tubular string;
• an adapter housing coupled to the mandrel;
• a guide sleeve disposed within the adapter housing and extending along a central axis;
• a movable sleeve disposed within the guide sleeve and configured for sliding axial movement within the guide sleeve;
• a retainer disposed within the guide sleeve at an axial location that is uphole of the movable sleeve, the retainer comprising:
• an upper annular portion and a lower annular portion axially spaced from the upper annular portion, wherein the upper annular portion is fixably coupled to the guide sleeve to restrict relative movement of the upper annular portion relative to the guide sleeve, and wherein the lower annular portion is fixably coupled to the movable sleeve;
• an annular void between the upper annular portion and the lower annular portion;
• and
• a bridge portion extending axially from the upper annular portion to the lower annular portion, wherein the bridge portion restricts the upper annular portion from moving relative to the lower annular portion, wherein the bridge portion includes a through-passage having a diameter D1 that defines a minimum inner diameter of the downhole tool, wherein the bridge portion defines a thin walled annular segment of the retainer having an outer diameter D2 that is greater than D1, wherein the thin walled annular segment is positioned radially adjacent to the annular void, wherein the bridge portion is configured to be milled to allow the lower annular portion and the moveable sleeve to move axially relative to the tubular adapter.