I was pleasantly surprised. Indian ink flows more freely than acrylic ink, which requires a bit of coaxing. But in total they work very well. You might need an additional tool (a small funnel, an eyedropper or a syringe) to avoid wasting ink or making a mess while filling the tank.
Fast shipping. Filled one with white ecoline to test it. No blotches. Fluent inkfliw. Thank you