Yaesu  XF-110C (YF-100)   500hz solder in CW filter in good shape and working fine. Label is a little tattered but it's a good filter.  This filter also may come from Yaesu marked as XF-455K-501-01 as in this case. This can be used in many Yaesu radios.  Please check your manual to make sure it will work in your radio.  This is a "must have" for the CW user. Buyer pays shipping for a well packed box. Buy from me with confidence as I have Excellent feedback.