Tunze USA 1076/2 Through The Back Overflow Box, Requires 1.75-Inch Bore Hole. Built-in overflow for lateral glass boreholes, diam. 1.75 in, on the rear or lateral wall of the aquarium, with surface and bottom suction up to about 400 US gal. For easy installation and quiet operation, we recommend the use of overflow hose set 1075/2.Uses standard 1.75 bore hole. This item is in the category "Pet Supplies\Fish & Aquariums\Filters". The seller is "buy_smart_love" and is located in this country: US. This item can be shipped worldwide.