Be proactive and replace the sensing foil BEFORE you pop an old 8 track into the player.  7/32" in width (slightly under 1/4") , 3/4" to 13/16" length, cut at a 60 degree angle.  30 pre-cut tabs, comes in a protective sleeve to keep the tabs from peeling up before use. 
 
As always, I use REAL sensing foil.  Designed for audio applications.  Paper thin so that it will not get hung up at the capstan shaft.  A cheap and easy way to help avoid the tape getting eaten due to the old sensing foil splice breaking!!
 
I realize these could in theory ship out in an envelope with a stamp on it.  However I only ship items with a tracking number.  This is for your benefit and mine.  So these do have to ship First Class Package unfortunately. 
 
Shipping Details:
 
USA Customers ONLY, Shipping is a flat fee of $4.13  
Orders $30 and over get FREE shipping via USPS First Class Mail.
 
Canadian Customers, Shipping is a flat rate of $14.96 via USPS First Class Small Package International Mail.
 
International Customers, I ship to most European Countries, and a few others. Shipping is via USPS First Class Small Package International and is between $17.96 and $19.33 for up to 5 items depending on what country you are in.
 
Also, depending on your country, you may be charged an excise tax on the value of the item. This is not included in the price and out of my control.