Mildliners are usually dual-ended: a broad chisel tip for highlighting and a fine or bullet tip for underlining, lettering, and detail work. Some listings also specify a 5 mm chisel tip.

Mildliner ink is described as soft and translucent; many listings call it a pigment-based, water-resistant formula that layers once dry, minimizes bleed-through on thin pages, and is low-odor and non-toxic.

Suggested minimum ages vary by set; examples from listings include 2 years and up, 6 years and up, 10 years and up, and 13 years and up. Check the specific product listing for the age recommendation.

Descriptions range from generic fine/bold labels to measured tip sizes. Listed examples include 0.4 mm, 0.5 mm, and 0.6 mm for fine tips and a 5 mm chisel tip for the broader end.

Mildliners are designed to minimize bleed-through on thin pages; listings and reviews frequently note that they resist bleeding and work well for Bible study, planners, and other thin-paper uses.