Permanent Protection from sewer vent frosting, GUARANTEED! The Sewer Skewer and the Sewer Skewer XL can both be purchased at Under the Sun Rental. Why make multiple trips up your roof in the dead of winter when you could simply insert a Sewer Skewer and be done with it? Sewer Skewers are all you need to keep sewer vents from frosting over, even at -25F!