Shoe base and foot shape problem in Your Avatar Posted July 16, 2016 Technically invisiprims were never supported. They are an exploit object kinda like megaprims. At one point someone discovered the alpha glitch in the Second LIfe matrix and invisiprims were created. When advanced lighting came along the exploit was exposed. And as discovered an appropriate 'alpha' is now needed to be worn on the base avatar to hide body parts.