What is the component of the microstop tool that prevents the adjustment sleeve from rotating?

The locking ring is a critical component of the microstop tool that ensures precise and controlled operation during the drilling process. Its primary function is to secure the adjustment sleeve in place, preventing it from rotating while adjustments are being made. This stability is essential because any undesired movement of the adjustment sleeve could lead to inaccuracies in the depth of the drill or the quality of the hole being drilled. By locking the adjustment sleeve, the locking ring helps maintain the integrity of the adjustments, allowing for consistent and repeatable results.

In the context of other potential components, the adjustment knob, while it allows for manual changes to be made, does not serve to prevent rotation on its own. The guide pin, on the other hand, typically assists in maintaining alignment or guiding movement but does not immobilize the sleeve. The cage holder usually serves a different purpose related to assembly and positioning, rather than preventing rotation. Thus, the role of the locking ring is fundamental to the tool's functionality, making it the correct choice for this question.