Cover is from Aug 30, 1891 mailed to Maidstone England with backstamp Rec 1891.
Listed as El Paso County, later became Woodland Park after first period Mar 19, 1888 - Feb 20, 1890.(I) Later became part of Teller County when formed in March 23, 1899.
GPU - General Postal Union 5 cent per 15 grams April 1, 1879 until UPU Universal Postal Union 1891 effective July 1, 1892 countries could choose 1/2 oz or 15 grams. Cover reflects the 5 cent rate for 15 grams to foreign destination.