security torx size?

hello all, sorry to bother you with such a small question, but i am going to change the MAF on my wifes 2000 gp, 3800, in a few days. there ia a small torx type security screw holding the MAF in place. i saw a set of these at a store a few weeks ago. is there a certain size i need to make sure is in the set? ...thanks...

T20 tamper proof bit.