Wow, look at this handyman dryer vent ducting!  I can see two sizes of vinyl, solid metal, flexible metal and- for good measure- let’s couple it with ABS drain pipe.  I’m not making this stuff up, I promise!  This was discovered at recent home inspection in Oak Harbor on Whidbey Island.  I always recommend installing solid metal ducting for safety reasons, and annually cleaning/maintaining as lint is flammable and can accumulate in dryer ducting.