Aquascape® Small Pondless® Waterfall with 6' Stream Flow Rate at 20 Feet of Head_3127 GPH 25" across bottom and 19-1/2"

25" across bottom and 19-1/2" top to bottom)

Here's a great Design and Installation guide from Savio for your reference

Prevents leaves and debris from falling into pond

Ideal for use with the Patio Pond

Aquascape® Small Pondless® Waterfall with 6' Stream Flow Rate at 20 Feet of Head_3127 GPH 25" across bottom and 19-1/2"Provide the sight and sound of cascading water into any landscape setting with Aquascape's small entry level professional Pondless Waterfall Kit. Includes enough liner to create a short 6' waterfall and stream. Kit Includes: 10' x 10' 45 mil Liner, 100 sq. ft. Underlayment 10' x 8' 45 mil Stream Liner Pondless Waterfall Vault Waterfall Spillway Three Small AquaBlox AquaSurge PRO 2000 4000 Pump 1. 5" x 25' Flexible PVC Pipe Pump Check Valve Assembly