ClenAir&reg; PurCool Condensate Pan Strip # 2001D , Treats up to 5 Tons This Item Ships FREE! Improves Indoor Air Quality (IAQ)...Prevents Drain Pan Overflows Good up to 5 tons , Lasts up to 6-months Long Lasting - Up To 6 Months , Helps Eliminate Foul Drain Pan Odors Supersedes / Replaces: 1903 , 1903-D , 2001 , 2001-D ClenAir , PurCool 'Sock' Strips , Nu-Calgon 61043 , 61047 , 1903-D100 , 1903D-100 , 61042 NuCalgon and many other Drain Pan Products.