Device with adjustment bolt

A device with adjustment bolt comprising:

• a bolt attachment wall having an internal thread hole;
• an adjustment bolt screwed with the internal thread hole and attached to the bolt attachment wall;
• a locknut screwed with the adjustment bolt;
• a cover fitted around the locknut, the cover having a tubular unit that surrounds the adjustment bolt and the locknut;
• and
• a stopper unit causing the cover to be in a removal disallowed state from the locknut,
• wherein the stopper unit includes a retaining ring, an attachment inner circumference unit provided in the cover so as to allow internal attachment to the retaining ring in the removal disallowed state, and an external circumference groove provided on the locknut so as to allow external attachment to the retaining ring,
• the external circumference groove includes a first groove portion and a second groove portion provided continuously with the first groove portion on a side of the bolt attachment wall, the first groove portion having a groove bottom that restricts removal of the retaining ring fitted within the attachment inner circumference unit from the attachment inner circumference unit due to contraction, the second groove portion having a groove bottom that allows removal of the retaining ring fitted within the attachment inner circumference unit from the attachment inner circumference unit due to contraction.