This is a battery cover for the Rival Perses. The Blaster is not included.
CREDIT: This is designed by ehdrian on Thingiverse and this is the unchanged version in Neon Green. The design files can be found here: https://www.thingiverse.com/thing:3852096
When the Perses' stock battery isn't installed the battery tray is wide open. This cover inserts into the Perses and uses the same latching mechanism as the included battery.
I've also included a small cutout in the battery cover to avoid damaging the Perses' stock battery contacts. Just in case any of you ever want to unmod your blaster and convert from LiPo to stock battery pack in the future.