These are possibly the best & highest quality 4-wall & a lid compost bins on the market. Made from 5 mm thick recycled plastic, these are much stronger than similar resin units. Walls include unique "active" aeration system - which provides superior air flow - increase action. The jewel composter is resistant with hinging lid & sliding "lock" to keep animals out. Walls are held together with "large" & heavy duty sliding "clips" - easy to disassemble. There are two doors to remove compost.