2.5mm allen key too large to loosen shift

[keppyuppy28]

hi i was trying quite successfully to to replace a broken brake lever on my mountain bike, i bought a new set and i had managed to take off the handlebar grip but as i proceeded[/size] to insert the 2.5 mm allen key up into the allen bolt i realized the allen key was too big. i dont have any sizes smaller , any idea what size i need for a SRAM GRIP SHIFTER MAX

[keppyuppy28]

hi i just had another look at it maybe the hole i was focusing on due to the positioning of the bolt on the shift is just part of the grub screw and the allen key is in fact too small , just measured it against a ruler and the key is 2mm so maybe 2.5mm is the correct size after all , pity my key is 2 4 5 and 6