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diff --git a/kamon-core/src/legacy-main/scala/kamon/metric/instrument/UnitOfMeasurement.scala b/kamon-core/src/legacy-main/scala/kamon/metric/instrument/UnitOfMeasurement.scala
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+++ b/kamon-core/src/legacy-main/scala/kamon/metric/instrument/UnitOfMeasurement.scala
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+/*
+ * =========================================================================================
+ * Copyright © 2013-2015 the kamon project <http://kamon.io/>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ * =========================================================================================
+ */
+
+package kamon.metric.instrument
+
+/**
+ *  A UnitOfMeasurement implementation describes the magnitude of a quantity being measured, such as Time and computer
+ *  Memory space. Kamon uses UnitOfMeasurement implementations just as a informative companion to metrics inside entity
+ *  recorders and might be used to scale certain kinds of measurements in metric backends.
+ */
+trait UnitOfMeasurement {
+  type U <: UnitOfMeasurement
+
+  def name: String
+  def label: String
+  def scale(toUnit: U)(value: Double): Double = value
+
+  def tryScale(toUnit: UnitOfMeasurement)(value: Double): Double =
+    if (canScale(toUnit)) scale(toUnit.asInstanceOf[U])(value)
+    else throw new IllegalArgumentException(s"Can't scale different types of units `$name` and `${toUnit.name}`")
+
+  protected def canScale(toUnit: UnitOfMeasurement): Boolean
+
+}
+
+object UnitOfMeasurement {
+  case object Unknown extends UnitOfMeasurement {
+    override type U = Unknown.type
+    val name = "unknown"
+    val label = "unknown"
+
+    override protected def canScale(toUnit: UnitOfMeasurement): Boolean = UnitOfMeasurement.isUnknown(toUnit)
+  }
+
+  def isUnknown(uom: UnitOfMeasurement): Boolean =
+    uom == Unknown
+
+  def isTime(uom: UnitOfMeasurement): Boolean =
+    uom.isInstanceOf[Time]
+
+  def isMemory(uom: UnitOfMeasurement): Boolean =
+    uom.isInstanceOf[Memory]
+
+}
+
+/**
+ *  UnitOfMeasurement representing time.
+ */
+case class Time(factor: Double, label: String) extends UnitOfMeasurement {
+  override type U = Time
+  val name = "time"
+
+  override def scale(toUnit: Time)(value: Double): Double =
+    (value * factor) / toUnit.factor
+
+  override protected def canScale(toUnit: UnitOfMeasurement): Boolean = UnitOfMeasurement.isTime(toUnit)
+}
+
+object Time {
+  val Nanoseconds = Time(1E-9, "n")
+  val Microseconds = Time(1E-6, "µs")
+  val Milliseconds = Time(1E-3, "ms")
+  val Seconds = Time(1, "s")
+
+  val units = List(Nanoseconds, Microseconds, Milliseconds, Seconds)
+
+  def apply(time: String): Time = units.find(_.label.toLowerCase == time.toLowerCase) getOrElse {
+    throw new IllegalArgumentException(s"Can't recognize time unit '$time'")
+  }
+}
+
+/**
+ *  UnitOfMeasurement representing computer memory space.
+ */
+case class Memory(factor: Double, label: String) extends UnitOfMeasurement {
+  override type U = Memory
+  val name = "bytes"
+
+  override def scale(toUnit: Memory)(value: Double): Double =
+    (value * factor) / toUnit.factor
+
+  override protected def canScale(toUnit: UnitOfMeasurement): Boolean = UnitOfMeasurement.isMemory(toUnit)
+}
+
+object Memory {
+  val Bytes = Memory(1, "b")
+  val KiloBytes = Memory(1024, "Kb")
+  val MegaBytes = Memory(1024 * 1024, "Mb")
+  val GigaBytes = Memory(1024 * 1024 * 1024, "Gb")
+
+  val units = List(Bytes, KiloBytes, MegaBytes, GigaBytes)
+
+  def apply(memory: String): Memory = units.find(_.label.toLowerCase == memory.toLowerCase) getOrElse {
+    throw new IllegalArgumentException(s"Can't recognize memory unit '$memory'")
+  }
+}