diff --git a/opm/material/densead/FastSmallVector.hpp b/opm/material/densead/FastSmallVector.hpp
new file mode 100644
index 000000000..f4ad8eb90
--- /dev/null
+++ b/opm/material/densead/FastSmallVector.hpp
@@ -0,0 +1,164 @@
+#include <array>
+#include <cstring>
+
+namespace Opm {
+namespace DenseAd {
+
+template <typename ValueType, unsigned N>
+class FastSmallVector
+{
+public:
+
+    FastSmallVector();
+    explicit FastSmallVector(const size_t num_elem);
+    FastSmallVector(const size_t num_elem, const ValueType value);
+    FastSmallVector(const FastSmallVector& other);
+    FastSmallVector(FastSmallVector&& other);
+    ~FastSmallVector();
+
+    FastSmallVector& operator=(const FastSmallVector& other);
+    FastSmallVector& operator=(FastSmallVector&& other);
+
+    ValueType& operator[](size_t index);
+    const ValueType& operator[](size_t index) const;
+    size_t size() const;
+
+private:
+    std::array<ValueType, N> small_buffer_;
+    std::size_t size_;
+    ValueType* data_ptr_;
+};
+
+template <typename ValueType, unsigned N>
+FastSmallVector<ValueType, N>::
+FastSmallVector()
+    : size_(0)
+    , data_ptr_(small_buffer_.data())
+{
+}
+
+template <typename ValueType, unsigned N>
+FastSmallVector<ValueType, N>::
+FastSmallVector(const size_t num_elem)
+    : size_(num_elem)
+    , data_ptr_(small_buffer_.data())
+{
+    if (size_ > N) {
+        data_ptr_ = new ValueType[num_elem];
+    }
+}
+
+template <typename ValueType, unsigned N>
+FastSmallVector<ValueType, N>::
+FastSmallVector(const size_t num_elem, const ValueType value)
+    : FastSmallVector(num_elem)
+{
+    std::fill_n(data_ptr_, size_, value);
+}
+
+template <typename ValueType, unsigned N>
+FastSmallVector<ValueType, N>::
+FastSmallVector(FastSmallVector&& other)
+   : size_ (other.size_)
+{
+    small_buffer_ = std::move(other.small_buffer_);
+    if (size_ <= N) {
+        data_ptr_ = small_buffer_.data();
+    } else {
+        data_ptr_ = other.data_ptr_;
+    }
+
+    other.data_ptr_= nullptr;
+    other.size_ = 0;
+}
+
+template <typename ValueType, unsigned N>
+FastSmallVector<ValueType, N>::
+FastSmallVector(const FastSmallVector& other)
+   : small_buffer_(other.small_buffer_)
+   , size_(other.size_)
+{
+    if (size_ <= N) {
+        data_ptr_ = small_buffer_.data();
+    } else {
+        data_ptr_ = new ValueType[size_];
+        memcpy(data_ptr_, other.data_ptr_, size_ * sizeof(ValueType));
+    }
+}
+
+template <typename ValueType, unsigned N>
+FastSmallVector<ValueType, N>&
+FastSmallVector<ValueType, N>::
+operator = (const FastSmallVector&other)
+{
+    small_buffer_ = other.small_buffer_;
+    size_ = other.size_;
+
+    if (size_ <= N) {
+        data_ptr_ = small_buffer_.data();
+    } else {
+        data_ptr_ = new ValueType[size_];
+        memcpy(data_ptr_, other.data_ptr_, size_ * sizeof(ValueType));
+    }
+
+    return (*this);
+}
+
+template <typename ValueType, unsigned N>
+FastSmallVector<ValueType, N>&
+FastSmallVector<ValueType, N>::
+operator = (FastSmallVector&& other)
+{
+    if (data_ptr_ != small_buffer_.data() && data_ptr_ != nullptr) {
+        delete [] data_ptr_;
+    }
+    size_ = other.size_;
+
+    small_buffer_ = std::move(other.small_buffer_);
+    if (size_ <= N) {
+        data_ptr_ = small_buffer_.data();
+    } else {
+        data_ptr_ = other.data_ptr_;
+    }
+
+    other.data_ptr_ = nullptr;
+    other.size_ = 0;
+
+    return (*this);
+}
+
+template <typename ValueType, unsigned N>
+FastSmallVector<ValueType, N>::
+~FastSmallVector()
+{
+    if ((data_ptr_ != small_buffer_.data()) && (data_ptr_ != nullptr)) {
+        delete [] data_ptr_;
+    }
+}
+
+template <typename ValueType, unsigned N>
+ValueType&
+FastSmallVector<ValueType, N>::
+operator[](size_t index)
+{
+  return data_ptr_[index];
+}
+
+template <typename ValueType, unsigned N>
+const ValueType&
+FastSmallVector<ValueType, N>::
+operator[](size_t index) const
+{
+  return data_ptr_[index];
+}
+
+template <typename ValueType, unsigned N>
+size_t
+FastSmallVector<ValueType, N>::
+size() const
+{
+    return size_;
+}
+
+}
+}