I used the free one and it seemed to give me about 30% better uptime. Since moving up to Gingerbread(2.3.3) I haven't used it. This is on the best phone ever made Droid X :D
Blatantly stolen from SD:bouncy:
Verizon has Droid X/X2 Essentials Pack for $19.97. Shipping is free.
Click http://www.verizonwireless.com/b2c/store/accessory?action=refineByPhone&phoneId=5658
Add to cart
Checkout: Total should be $19.97
Essential Pack includes
HDMI cable
Multimedia station...