One of the advantages of modular plastic belt conveyors is that they can be fitted with higher and thinner cleats or flights than normal PVC belts.
The added advantage is that these flights are rigid plastic, rather than the more flexible type of cleats that PVC belts usually have.
Also, the pitch of these flights is accurate, because they are links on to the chain belt and are therefore on a totally predicable pitch and are also always square to the belt.
These factors are advantageous where high accuracy positioning is required where the conveyor belt is used for pick and place or other precise movement.