text: May need some adjustment (Trial and Error)
  
  This product is quite sturdy (metal not plastic). Easily installed. However the flow restriction is more like 70%. Using a 1/16 inch drill bit, I drilled a hole in the center of the perforated plastic insert. That increased the flow but not to rinse the shampoo from my wife's hair. Through measured process I ended up drilling 2 additional holes (12 and 6 o'clock) for a total of 3. Just like Goldilocks I got it "just right."