Replacement Yamaha TTR90 / TTR90E air filter, made in USA. It is shipped un-oiled; add ~2 caps of oil to the filter and squeeze/work it for a minute in the supplied plastic bag, then install. 

FAQ: 

• How do I oil the air filter? 
• Put ~2 caps full of oil on filter. Motor oil, 2 stroke oil, bar oil are both fine for this. 
• Put filter in bag and squeeze filter to work the oil into the filter. The bag saves your hands getting messy
• Install
• What kind of foam is used for the filters? 
• OEM spec small pore polyurethane filter foam
• It is fuel safe and washable with soap and water. 
• Is this an OEM filter? 
• It's a functional replacement for the OEM filter
• How are the filters produced? 
• Filters is die cut and made in USA