Binary Search For Data Types With Relation Operators

I am trying to write a binary search algorithm to work with any data type that is defined to work with the relational operators and returns the position of the found element. I want to know if there is anything I need to be aware of when dealing with user defined types. As well as any flaws or improvements that I can make. Also one other question is how does my search compare to the built in binary_search function?

#include <iostream>
#include <iomanip>
#include <type_traits>

template<typename T, typename U>
U BinarySearch(T *arr, T toFind, U _size){ //make return type same as size for overflow issues
    static_assert(std::is_integral<U>::value, "Integral type required for size of array");

    U mid, low = 0, high = _size-1; //maintain same integral types
    T m, l = arr[low], h = arr[high]; //maintain same T types

    while(l<=toFind && h>=toFind){
        mid = (high + low)/2;
        m = arr[mid];
        if(m > toFind){
            h = arr[high = mid - 1];
        }
        else if(m < toFind){
            l = arr[low = mid + 1];
        }
        else
            return mid; //postion point + 1
    }

    //exits if not found
    return -1;
}

const auto SIZE = 10;

int main()
{
    double arr[SIZE] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.1};
    auto pos = BinarySearch(arr, 1.1, SIZE);
    std::cout << pos << '\n';
    return 0;
}

Thanks for all your advice in advance.