There are two options for the BP17
Option 1: If you would like to keep the factory shroud and add a suppressor to the end of it get #A49
Option 2: If you would like to remove the factory shroud and keep the gun as short as possible with a suppressor, select #A74. This is the version Ted did a review on.
*Make sure to get a suppressor one caliber size above what your gun is. Still very effective and reduces the chance of pellet clipping.