This will depend on whether you are going to re-use existing latch mechanisms etc that may be present in your door(s). Depending on what new handles/knobs you are planning on fitting, you may not need to buy new if your existing mechanisms are in decent working condition. It is for this reason that door handles are not automatically supplied with latches and locks – there are so many different eventualities. If you are buying door knobs, most are supplied unsprung so we recommend the a heavy duty mortice latch as the springing will ensure the knobs do not get ‘stuck’ in the open position when in use. This can happen when a cheaper contract latch is used. For door handles on a backplate, you can buy any mortice latch as all handles on plate are pre-sprung. Bathroom doors will need a mortice bathroom lock. Check out our door handle buying guide for further info.