This is a compatible  battery to fit the following models when fitted with a button release type battery: DC31,DC34,DC35,DC44. This model is obselete so genuine batteries cannot be purchased. 
 
There are two types of batteries for these models. One is secured with a screw (Type B) and this one (Type A) is what is called a “push fit” where the battery is released with a button on the back of your vacuum handle.
 
* Do not leave your cordles Dyson on charge all the time. They only take 3-4 hours to charge, once fully charged switch them off at the plug socket to prolong the life of your battery*