Seal chain

A seal chain comprising:

• two inner link plates opposed to and spaced apart from each other;
• a tubular bushing, opposite ends of the bushing being respectively joined to the two inner link plates;
• a pin rotationally inserted into the bushing;
• a tubular roller into which the bushing is inserted, the roller being rotationally supported by the bushing;
• and
• two outer link plates arranged to externally hold the two inner link plates in between, opposite ends of the pin being respectively joined to the two outer link plates,
• wherein a recess into which an end of the roller is inserted is formed in an inner surface of each of the inner link plates, wherein
• a retainer ring is coupled to an outer circumferential surface of the bushing,
• an accommodation groove that accommodates the retainer ring is formed in an inner circumferential surface of the roller,
• the two inner link plates are opposed to and spaced apart from each other in a width direction,
• the two outer link plates are arranged to externally hold the two inner link plates in between in the width direction,
• a first gap is formed between the retainer ring and the accommodation groove in a radial direction of the retainer ring, and
• second gaps are formed between the retainer ring and the accommodation groove in the width direction.