With the AAC Illusion, AAC was able to produce the FIRST 9mm pistol suppressor that is truly compatible with factory sights. The problem with round suppressors on pistols is that they tend to block the factory sights. That can be worked around by replacing the sights with either an optic or higher "suppressor" sights; but, eccentric suppressors solve the problem altogether! For more information http://www.silencershop.com/silencers/pistol/aac-illusion-9.html