These universal 45" lead wires are a great replacement for your old lead wires and are nice to have handy as a pair of extras for when you need it. They are very compatible with most TENS unit and EMS muscle stimulators. Lead wires should be replaced every 4-6 months, which is why it is good to have multiple lead wires in your inventory. These universal lead wires come 2 per pack and are standard for most TENS, EMS and IF units.