Shower arm diverter valve

[Rmike]

Hi all
I'm trying to add an all metal/brass shower arm diverter valve to have a shower head and handheld. There are many different valves on the market but I couldn't find any that would not restrict the water flow. Here are some pictures (with reviews) I got online to show you what I mean.
I would really appreciate your hep in finding the right valve that is not going to restrict the water flow and loose the water pressure on either side
Thank you in advance

 

[Terry]

Most hand showers and shower heads are restricted to about 2 gallons per minute. How much are you going for?

 

[Sponsor]

 

[Rmike]

Both - my handheld and the shower head are 2.5GPM. I just want to use that pressure

 

[WorthFlorida]

Mandated by the EPA, 2.5 gallons per minute is the max through to the shower heads total, not each.

https://www.epa.gov/watersense/showerheads
Shower With Power
Product Specification Review
EPA is requesting information that will help it assess consumer satisfaction with products in order to support further improvements in water efficiency and/or product performance. Learn more.

Did you know that standard showerheads use 2.5 gallons of water per minute (gpm)? Water-saving showerheads that earn the WaterSense label must demonstrate that they use no more than 2.0 gpm. The WaterSense label also ensures that these products provide a satisfactory shower that is equal to or better than conventional showerheads on the market. EPA worked with a variety of stakeholders—including consumers who tested various showerheads—to develop criteria for water coverage and spray intensity. All products bearing the WaterSense label—including water–efficient showerheads—must be independently certified to ensure they meet EPA water efficiency and performance criteria.

 

[Rmike]

I'm not trying to do anything illegal. If one of those devices is connected directly to the line it'll give me whatever is set to at the factory GPM. By installing the diverter valve I'm not going to use twice as much water because only one device will be used at the time. Based on people's reviews online all those valves are reducing the pressure and this is what I'm trying to avoid. Maybe I didn't make myself clear in my initial post. Basically I need the diverter valve that will match the specs of the devices that I have so I will not loose any pressure.