Pimple rubbers..... how to define the difference and usage?

[TareqPhoto]

What is this pimple rubbers designed for? and what is the main difference between the short, medium and long pimple rubbers in use?

How you decide which pimple rubber to use? and with sponge or no? if with sponge, then what thickness you think/feel/prefer to use?

 

[Old School]

I'm not a pimple expert but I would categorize them like this.

Short
Most sensitive to incoming spin close to inverted rubbers.
With a fast sponge good for hitting and smashing.
With slow sponge good for blocking / chopping.

Long
Almost no sensitivity against incoming spin unless played with thick sponge or very grippy pips.
Will reverse incoming spin depending on the pips played and stroke used.
LP is popular amongst amateurs with no sponge as it give the most reversal when playing a blocking/pushing game close to table.
The more sponge used with LP the more reversal you can add with your stroke but it becomes harder to stay close to the table so it's mostly used away from the table copping.

Medium is a mix between short and long, good at both short and long style play but master of none.