Are these safe for sensitive or nickel-allergic ears?

The maker states the studs are hypoallergenic stainless steel and lab-tested free of nickel, lead and cadmium. That makes them a reasonable choice for sensitive ears, though individual reactions vary.

How big are the hearts?

Each heart measures about 3mm wide by 3mm tall, so they sit close to the earlobe and read as a small accent rather than a statement piece.

What kind of backing do they use?

They have a flat screw-back closure on a 9mm post at 20 gauge (0.8mm). The screw thread holds the back in place more securely than a push-on butterfly.

Can I wear them in the shower or while sweating?

The maker describes them as waterproof and sweat-proof for everyday wear. The gold PVD finish is more durable than plating, but rinsing and drying them after heavy exposure helps them last.

Are they a good gift for a tween?

The small heart shape, secure screw-backs and sensitive-ear materials suit girls and tweens. The tiny size and small parts mean younger children should be supervised.