The Paul Mitchell Neuro Smooth 1.25" is a flat iron whose primary function is straightening hair; its 1.25-inch CeraShine ceramic-blend plates also have rounded, beveled edges that let the same iron be turned to add waves, curls, or flips as a secondary use. A SmartSense microchip continuously monitors and regulates plate temperature to maintain even heat across the plate surface and reduce hot spots during a pass.

Temperature is adjustable up to a maximum of 450°F (230°C), shown on a digital display that toggles between Fahrenheit and Celsius. Paul Mitchell's own hair-type guide suggests roughly 160-300°F for fine hair, 310-390°F for medium hair, and 400-440°F for coarse hair, reserving the full 450°F setting for professional use. The iron reaches 450°F in about 45 seconds, and a memory function recalls the last temperature setting used.

The cushioned plates and beveled edges are intended to reduce demarcation lines — the visible marks a plate edge can leave in a section of hair — for a smoother pass overall. Other features include a 9-foot professional-length swivel cord, automatic dual voltage (110-240V) for use outside North America, and an automatic shutoff after 120 minutes of inactivity. Paul Mitchell backs the iron with a 12-month limited warranty, extendable to 24 months with product registration.

At 1.25 inches, the plate width sits between Paul Mitchell's narrower 1-inch Neuro Style+ and its wider 1.75-inch Neuro Smooth+, making it the mid-size plate option within the same Neuro line, generally suited to a broader range of hair lengths than either sibling.

To straighten hair with this iron, start with hair that is clean, fully dry, and detangled, and apply a heat protectant. Set the temperature according to hair type using the ranges above. Working in horizontal sections roughly 1-2 inches wide, clamp the iron close to the root and glide it slowly and steadily down to the ends in a single pass, keeping even pressure on the section throughout. Because the plates are cushioned with beveled edges, the iron can also be rotated about a half turn at the point where a bend is wanted and pulled through to the ends with light tension, adding a wave, curl, or flip once the section has already been smoothed straight.