Chris,
All the Induction Noise Suppressor boxes serve the same purpose .
INS box is originally designed by Serpent, In 1995 IFMAR, the World organization for RC racing, asked the manufacturers to come up with solutions to reduce the noise-level of 1/8 scale gas powered racing cars. Serpent took up the challenge and in close co-operation with the University of Delft, developed the universal Induction Noise Silencing Box, the INS-BOX. In combination with an effective (*) exhaust silencer, the INS-BOX is able to reduce the overall sound level with up to 4 decibels. If 10 cars would be using the INS-BOX at the same time, like in a race, the overall noise-level would drop with 5 to 6 decibels!

Source: http://www.serpent.com/product/200305