The option to customize your flashing based on your roof type, your tubing length based on your attic height and your ceiling fixture. For roof pitches of 0:12 to 3:12 a no pitch flashing is recommended and for 4:12 to 12:12 a pitched flashing is recommended. Measure your attic height to decide which length of tubing you need, tubing can always be cut to fit. And finally, there are several decorative fixture options for your ceiling, but all kits come standard with a Vusion diffuser.