From the PE link just above your post:
"PRV Audio's WG35-25-B waveguide is designed to emulate the sound of a QSC PL-000446GP waveguide, which is popular with Econowave DIY speaker builders! This 90° x 60° waveguide is designed to be used with 1" 2-bolt compression drivers, and allows for crossover points as low as 1,000 Hz due to how it loads the driver, resulting in amazing off-axis power response.
Specifications: • Horn type: Exponential • Minimum frequency: 1,000 Hz • Nominal dispersion: 90° H x 60° V • Throat diameter: 1" • Mounting type: 2-bolt • Dimensions: 10.1" H x 14.2" W x 5.5" D."
I think someone at PE or PRV is confused. They seem to be a pretty good approximation of the original QSC flare. Also they are cheap! I got 4 of them last year, one pair has the cheapo PRV drivers on them. Not all that impressed with the drivers. The other pair got drilled out to fit a 1.4" Altec clone driver. Now that set is nice!
Page says clearance, get 'em while you still can, although to be honest, it said that last year too.