2X([Suitable for Bottleneck Size 24-410]-- Mainly used in the market for 2 oz acrylic paint bottles. May fit other 1 oz, 4 oz and 8 oz bottleneck sizes 24-410. You can change the cap directly to switch different types of needles, so you don't have to change the whole bottle, which is very convenient to use and saves a lot of trouble. ).