Abstract: A headrest stay includes a detachment prevention slot portion formed in a rod-shaped leg portion, the detachment prevention slot portion being recessed toward a center side of the leg portion, the lock portion being configured to enter into the detachment prevention slot portion, and the detachment prevention slot portion including: a first flat face portion that faces a lower side; and a second flat face portion that faces an upper side, the second flat face portion including: an opposing portion that opposes the first flat face portion; and a region that, in a vertical sectional diagram cut along the axial direction of the leg portion, is disposed at an outer peripheral side of the leg portion relative to the first flat face portion.

Abstract: A cam follower with a roller for use with an engine, the roller adapted for rolling contact with a cam on a camshaft. The roller is formed with minute recesses arranged in random directions so that an RMS(L)/RMS(C) ratio is not more than 1.0 wherein RMS(L) and RMS(C) are surface roughness root mean square values in the axial and circumferential directions, respectively. An SK value, another surface roughness parameter, should be not more than -1.6. This degree of roughness represents a higher surface roughness than prior art cam followers, provides greater oil retention and therefor better lubrication.