Tremolo back plate for Strat-style guitars.
Polished brass, coated with a chrome layer, just like vintage Schecter.
On a vintage Schecter Dream Machine the tremolo back plate was normally of metal, in this case chromed brass.
Theoretically each piece of metal within the pickup's magnetic field will have an effect on the sound of the pickup. In case of the tremolo plate (in contrast to the pickguard!) this effect might be neglectable. For originality, and the 'vibe' of your replica guitar, it might be not! Also it will change the weight, and with this the resonance frequencies of the guitar.
Traditional Fender / Schecter ('vintage') dimensions.