The LUCKY SEVENS are not designed to replace conventional whale-tails, but are designed to allow the PDR technicians to get to panels and locations that were previously inaccessible. Any 1/2" can serve as an entry point for the "7"s.
Heat-treated stainless steel allows for some flexibility in the shafts to "snake" to the dent. While the "7" notch in the head design allows for unparalleled access to panels, some torque strength is also removed from the tool.
A-1 Tool offers them in 6", 10", 20" and 30" diameter.