Is the 3 in. and 4 in. Adjustable Pipe Flashing with Hard Plastic Base and Rubber Collar, a no-caulk item?

There is no sealant necessary at the base of the pipe.

There is no sealant necessary at the base of the pipe but it is recommended to seal over the nails that are used to connect the base to the roof as this penetration can leak if not properly sealed.