Is this sweater actually 100% cashmere?

Yes. The description lists cashmere as the material, with a rib-knit high collar, rib-knit cuffs and hem, and a plain stitch body. It is made in Italy.

How should I care for a cashmere turtleneck?

Hand wash in cool water with a cashmere shampoo or dry clean, then dry flat away from heat. Fold it rather than hanging, and use a knit comb on any pilling.

How does it compare with cheaper cashmere turtlenecks?

The difference is mainly the yarn and finishing: finer, softer cashmere and neat Italian rib trims. Cheaper versions often use shorter fibers that pill faster and thinner collars that lose shape.

What is the fit like?

The description gives no fit details beyond the rib-knit collar, cuffs and hem. Treat it as a regular men's knit and check the measurements before ordering if you want a slim or relaxed look.

Can it be worn under a jacket?

Yes. The plain stitch and rib trims keep it low-profile, so it layers under a blazer or coat. The high collar adds warmth at the neck, so leave room in the jacket collar.