POR Series steel oil reservoirs are holding vessels for standby oil necessary for the operation of a commercial refrigeration or air conditioning system. Two models are available. The POR-2 has a capacity of 2 gal and is 18-in. long. The POR-4 has a capacity of 4 gal and is 36-in. long. Other features include: two sight glass ports for oil level monitoring; 3¼8-in. flare Rotolock valves on the top and bottom to allow isolation of the reservoir for addition or removal of oil; and a vent port for connection to the suction line to prevent pressure buildup, says the manufacturer. Parker Hannifin Corp., Refrigeration Service Center, 2445 S. 25th Ave., Broadview, IL 60155-3858; 800-742-2681; 800-424-7109 (fax); www.parker.com/cicam (website).