Overview Reviews Product Description There are two common ISO Hydraulic coupler styles deployed in North America, those being the ISO-A and ISO-B classes.Both ISO A & B male nipples are differentiated by their sloped locking angles versus the sharper angled profile of the common PioneerĀ® design. Greenline Industrial Fitting Catalog New Greenline Industrial Fitting Catalog Product Videos Custom Field Product Reviews Write a Review Write a Review × Greenline 1/4" ISO "B" Hydraulic Dust Cap C109-04 Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Review Subject * Comments *