Only the other drops that already come with the marker.
Pirahna GTI, 32* whisper barrel, PMI expansion chamber, 20 oz pure energy co2,
Described in review
Nothing that i found
Strength-The drop brings your marker more up clsoe to your body that lets you squeeze in tight places and still lets you shoot at an angle but it sort of gets in your way if your laying down or set it on a ledge and shoot. This is an excellent drop if you play air-ball but for woodsall it gets in your way when you shoot
If you play woodsball i wouldnt highly recommend it but i would if you play airball