Straitjackets, while amazingly good at containing ponies, can be a bit of a hassle sometimes. So the developers at MTI (MareTech Industries) have made what is called a ‘Cradle’ suit.
 
While many versions and materials exist, this one is the Isolation Cradle, as modeled (Perhaps unwillingly) by one Rainbow Dash.
 
The main features of the Cradle suits are restraining all four hooves on the pony, keeping them folded to their body in their own special pockets. This forces them into a sitting pose until released.  
This model is one of heavy latex with attached blinding hood, earplugs and a gag. More common models end just below the head in a collar. A handle on the back allows easier transportation by pegasus and earth ponies. They are commonly used to transport dangerous individuals until they can be restrained properly afterwards.
 
 
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Ponies in latex, expect more of these…