Dryer drum support roller. If the dryer is making a rumbling or knocking noise the rollers may be worn out causing the drum not to turn smoothly.
XP702HD Heavy Duty Dryer Drum Roller Replaces 3388342, 3389902, 3396801, 3396802, 3401846, 8536973, 8536974, W10314171, W10314173, W1031473, W10756057, WPW10314173