‘5537’ are Fine Avery Dennison’s Fabric Plus Fastener. The size of the needle is 3” Long. These fasteners are specialised for the system 1000 model and micro tagger. These fasteners are used for creating a unique design for delicate applications that reduces the risk of holes and snags. We are always happy to help with your custom specific needs, please call us 1-800-426-5708.