New England Custom Guns (NECG) is a great source for express sights. Personally I love this rear sight, it features a clamp so you can adjust windage more easily with this sight.
The standing sight height over barrel is .670″, the first leaf is .650″, the second leaf is .670″ . The sight base is available in four barrel diameters, you must select the closest candidate when ordering.
Many Americans tend to order express sights with three (3) folding leaves. This may be traditional looking, but for most shooters it is a waste of time and money. I generally recommend to clients that they use either a single fixed express blade or a sight with a single folding leaf. The reason being, you don’t often have time to choose the sight, and if you do few shooters are comfortable today with a wide open V sight at more than 200 yards.
I normally file in the rear fixed blade for 25 yards since this will allow for snap shooting for any distance from the muzzle to 50 yards with no thoght about trajectory. Then the first folding leaf I file for 150 or 200 yards depending on the owners wishes and the caliber of the rifle. When deciding on distances look at the trajectory for your chosen load to decide sight height.
Some shooters do not realize that such sights are normally filed to the particular ammunition you plan to shoot. If you switch loads on a gun with express sights be sure to test the loads at the range for point of impact. New loads will not only change elevation, often windage will be affected as well.