Microloading is an extremely effective technique to break through your plateau and make continual progress and gains. The leap between traditional weight sizes can be a big load for your muscles and nervous system to handle as a percentage difference.
This industry standard in weight increments is not relevant to you, your workout or how we train but is purely for affordability which can cause many people to continue using the same maximum weight for which their body has become accustomed and not progress. Adding a small enough weight can mean completing the same amount reps you would normally complete but with the extra weight loaded. This could mean in some exercises you could progress by 1kg every week!
Machined from a solid steel bar
Plates embossed with weight rating