diff --git a/examples/MQ-135/MQ4.ino b/examples/MQ-131/MQ-131.ino
similarity index 70%
rename from examples/MQ-135/MQ4.ino
rename to examples/MQ-131/MQ-131.ino
index 613a5a8..832fa27 100644
--- a/examples/MQ-135/MQ4.ino
+++ b/examples/MQ-131/MQ-131.ino
@@ -1,7 +1,7 @@
 /*
-  MQUnifiedsensor Library - reading an MQ4
+  MQUnifiedsensor Library - reading an MQ131
 
-  Demonstrates the use a MQ4 sensor.
+  Demonstrates the use a MQ131 sensor.
   Library originally added 01 may 2019
   by Miguel A Califa, Yersson Carrillo, Ghiordy Contreras, Mario Rodriguez
  
@@ -18,22 +18,22 @@
 
 //Definitions
 #define pin A0 //Analog input 0 of your arduino
-#define type 4 //MQ4
+#define type 131 //MQ131
 
 //Declare Sensor
 
-MQUnifiedsensor MQ4(pin, type);
+MQUnifiedsensor MQ131(pin, type);
 
 void setup() {
   //init the sensor
-  MQ4.inicializar(); 
+  MQ131.inicializar(); 
 }
 
 void loop() {
   //Read the sensor
-  int read =  MQ4.readSensor();
+  int read =  MQ131.readSensor();
   //Print measurements
-  Serial.print("MQ4: ");
+  Serial.print("MQ131: ");
   Serial.print(read);
   Serial.println(" PPM");
   //delay 1s to next measure
diff --git a/examples/MQ-303A/MQ4.ino b/examples/MQ-135/MQ-135.ino
similarity index 70%
rename from examples/MQ-303A/MQ4.ino
rename to examples/MQ-135/MQ-135.ino
index 613a5a8..942a860 100644
--- a/examples/MQ-303A/MQ4.ino
+++ b/examples/MQ-135/MQ-135.ino
@@ -1,7 +1,7 @@
 /*
-  MQUnifiedsensor Library - reading an MQ4
+  MQUnifiedsensor Library - reading an MQ135
 
-  Demonstrates the use a MQ4 sensor.
+  Demonstrates the use a MQ135 sensor.
   Library originally added 01 may 2019
   by Miguel A Califa, Yersson Carrillo, Ghiordy Contreras, Mario Rodriguez
  
@@ -18,22 +18,22 @@
 
 //Definitions
 #define pin A0 //Analog input 0 of your arduino
-#define type 4 //MQ4
+#define type 135 //MQ135
 
 //Declare Sensor
 
-MQUnifiedsensor MQ4(pin, type);
+MQUnifiedsensor MQ135(pin, type);
 
 void setup() {
   //init the sensor
-  MQ4.inicializar(); 
+  MQ135.inicializar(); 
 }
 
 void loop() {
   //Read the sensor
-  int read =  MQ4.readSensor();
+  int read =  MQ135.readSensor();
   //Print measurements
-  Serial.print("MQ4: ");
+  Serial.print("MQ135: ");
   Serial.print(read);
   Serial.println(" PPM");
   //delay 1s to next measure
diff --git a/examples/MQ-131/MQ4.ino b/examples/MQ-303A/MQ303.ino
similarity index 76%
rename from examples/MQ-131/MQ4.ino
rename to examples/MQ-303A/MQ303.ino
index 613a5a8..0abb94a 100644
--- a/examples/MQ-131/MQ4.ino
+++ b/examples/MQ-303A/MQ303.ino
@@ -1,7 +1,7 @@
 /*
   MQUnifiedsensor Library - reading an MQ4
 
-  Demonstrates the use a MQ4 sensor.
+  Demonstrates the use a MQ303 sensor.
   Library originally added 01 may 2019
   by Miguel A Califa, Yersson Carrillo, Ghiordy Contreras, Mario Rodriguez
  
@@ -18,22 +18,22 @@
 
 //Definitions
 #define pin A0 //Analog input 0 of your arduino
-#define type 4 //MQ4
+#define type 303 //MQ303
 
 //Declare Sensor
 
-MQUnifiedsensor MQ4(pin, type);
+MQUnifiedsensor MQ303(pin, type);
 
 void setup() {
   //init the sensor
-  MQ4.inicializar(); 
+  MQ303.inicializar(); 
 }
 
 void loop() {
   //Read the sensor
-  int read =  MQ4.readSensor();
+  int read =  MQ303.readSensor();
   //Print measurements
-  Serial.print("MQ4: ");
+  Serial.print("MQ303: ");
   Serial.print(read);
   Serial.println(" PPM");
   //delay 1s to next measure