These puncture-proof sack truck spare wheels are ideal for heavy-duty use when moving loads with your sack trucks, hand trucks, trolleys, carts, dollies, wheelbarrows, etc., even on uneven grounds. The solid tyres are made of durable, abrasion-resistant PU elastomer and have a special tread design that provides added grip at higher speeds. The wheel rims are made of sturdy plastic. The spare trolley wheels have a universal size and can be easily installed to your sack trucks, trolleys, etc. Delivery includes 4 wheels.