Each Transit slide lock comes with the plastic base - which needs to be clicked together, 4 plastic feet (which replace the rubber feet on your fridge-freezer) and mounting screws. Durable, corrosion resistant construction. more tools. Simple, Self-locking mechanism. Easy one-touch release system. Easy to follow instructions inside. Engel Transit Slide Lock 530/540 - fits Engel models MT35, MT45 and MR040 (MR040 requires Adaptor Kit sold separately) and are highly recommended from a safety point of view. They help prevent your Engel fridge/freezer from shifting around in a vehicle or boat. Securely attach your transit slide lock to the vehicle and then simply slide your Engel into position and it locks down automatically. To remove, just push the clip to release. It is that easy! The Slide Locks work with all Engel Transit Bags.