Appears on page 81 of GURPS Dragons worth -15, not available to Horizontal (worth -10) or Semi-Upright (worth -5)
Introduced in GURPS Bestiary
Foot Manipulators combined with the Modifying Beings With One or Two Arms rules would only give -6 for a pair of arms that can only be used when legs are out of commission, implying this might be overpriced.