Steripen Classic 3 and the pre-filter have  never been used.  The pen sells for $99 new on Amazon and the Pre-filter sells for $39 new on Amazon.

From a non smoking home.

Trusted on mountains and trails for over 15 years, the Sterpen Classic 3 is an excellent choice for UV Water Purification. Ultraviolet (UV-C) light rays efficiently purify clear water by inactivating 99.9% of protozoa (including Giardia and Cryptosporidium), bacteria and even viruses. When the treatment is complete, LED indicators flash to let you know that the water is ready to drink. Approximate number of activations using the various battery chemistries: Alkaline (25), Lithium (150) or Rechargeable NiMH (100).

SteriPEN Pre-Fiter removes particulates from water. Use alone or to ready water for treatment with a SteriPEN handheld, UV water purifier.

SteriPEN Pre-Filter fits the openings of Nalgene and comparable wide-mouth water bottles and can be stored on bottle.

Features a durable 40-micron filter cartridge to remove particulates from water when filling bottle by submerging or pouringwater into filter.

Makes purification easy - insert SteriPEN handheld UV water purifier into center of Pre-Filter, turn bottle upside down and agitate to treat water.

SteriPEN Pre-Filter stores easily the your Nalgene bottle when you're on the go.