Incremental modules get “Rate” values, that is, items by second (bytes by sec ) in case of traffic.
This type of module is created this way because in SNMP all meters are useful to measure a value rate by second. Doing it with absolute values would be tricky because if the values are not exactly the same, will give values that shouldn’t be compared.
This way you will see peaks in the graph that would be incorrect because the measure interval would be higher than the previous one making all false. Though a rate (x/sec) is perfectly comparable to another rate (x/items/sec).