Retractable/clickable toppers typically have a push-button mechanism to extend and retract the eraser, accept refill eraser leads (often two refills), include a clip for attaching to notebooks, and have a pen-like shape and length for comfortable handling.
Refillable retractable toppers are commonly described as including two refill erasers per unit.
Novelty erasers are often promoted as party favors, treat-bag fillers, classroom prizes, and fun additions to school supplies or gift bags.
Some novelty erasers include choking-hazard warnings for small parts, and several sets list suitability for children aged 4 and up.