People taking aerobic classes for the extra load and the ease of changing weight amounts by picking them up or setting them down between exercises.
Martial artists can use them whilst punching or going through their routines to add resistance.
They are so easy to just stuff into a bag or backpack when finished using them.
People who like to work out on the go.
Elderly because they are not hard enough to break small bones or brittle bones due to osteoporosis
Physically challenged
People rehabilitating from injury or muscle deterioration. It may be hard for some people to even hold onto a 1 kilo weight and need it to be safe Gym users needing variety from using dumbbells.
SedentaryProfessionals
Office workers can pick them up to relieve the tedium of sitting too long at the desk not getting any exercise
People on long journeys with little space to move around. Any extra help in tight quarters helps so even just raising one’s arms above the head can be beneficial
Jugglers who wish to also build strength with their coordination
Military
For the military. The whole set can be carried in a backpack and and disassembled for use in a remote place and packed up quickly and efficiently for moving again.