Sealants dispensed from standard caulking tubes can be a little messy to work with when you are trying to lay down a very thin bead. One "trick of the trade" is to apply the sealant with a syringe. No needle, of course.
These large 60cc syringes are the perfect size for sealing around windows, vents and seams. Choose either 1/16" or 3/16" diameter opening.
And because they're inexpensive and disposable, cleanup is a breeze. You'll want to order several so you always have a few on hand.
To give you an idea of how big a 60cc syringe is, it is approximately 1/4 cup.