136g Corner 1/4 Cylinder Glass Reef-Ready Aquarium Set in WalnutAqua Vim glass tanks come with built in three level intake overflow boxes (larger tank sizes have 2 overflows) and predrilled 1. 5" drain and 1" return holes for plumbing. Tanks are top braced with glass rims for maximum structural integrity. The drilled feeder hole in the brace of the tank allows for accessibility and convenient feeding. For ease of setup, dual openings in the back corners of the brace allow for customization and wiring of internal