Device including rotator and belt, such as a fixing unit for an image forming apparatus

A device comprising:

• a rotator having a rotation axis;
• a belt configured to move in a moving direction orthogonal to the rotation axis;
• a nip forming member surrounded by the belt, the nip forming member configured to, with the rotator, pinch the belt to form a nip;
• a holder including a support wall, the support wall having a first surface and a second surface opposite to the first surface, the first surface being configured to face the rotator and support the nip forming member, the second surface having a plurality of ribs, the plurality of ribs being arranged in a width direction parallel to the rotation axis and spaced from one another, and each of the plurality of ribs extending in the moving direction and protruding from the second surface;
• and
• a first stay surrounded by the belt and extending in the width direction, the first stay being configured to support the holder by contacting the plurality of ribs;
• and
• an urging member urging the first stay toward the rotator.