The Thunder B grenade is hands down the most cost effective enhancer to any airsoft game I've ever played. The grenade itself, in all of its spoon flinging/noise producing glory, is extremely simple to use and even though you cannot reuse the shells it is still extremely cheap compared to anything else on the market. Recently, Hakkotsu introduced a little bit of an update to the shells which includes the hard plastic ring for the top and bottom of the shell. It helps dramatically since it improved the structural integrity of the shells - they no longer give in to stress on the weak points. When they did that it would create only a little hole in the shell allowing CO2 to decompress from the shell without making a loud bang. With the rings, the shells hold up nicely and usually always bust open like they're supposed to creating a huge bang.
-Cheap. Extremely cost effective even though it is simply a sound device. At this price it would not be impossible to get a few over time and have multiple grenades for a single game (it's hard to reload mid-skirmish).
-Effective. It makes opponents scream like a little girl 90% of the time they see one chucked their way.
-Simple use. The internal set up of the grenade is perfect. Kind of makes you feel like an explosives expert without any danger of ANYTHING exploding. I mean, you don't even have to worry about the CO2 canister going off. The hammer is sort of tricky to pull back into place but there are youtube videos to see how to do it the easiest way.
-Replacement parts galore. I've lost a ring and a pin...No need to fear, you can buy all parts very cheap. Not to mention a bunch of spare shells are even really cheap.
-Sturdy. The spoon has never detached from mine even throwing it 30+ feet repeatedly. The new rings are super strong, the pin has a tendency to bend but then again...it is only a pin, and the guts of the grenade are really well machined metal and other hardware.
-The hammer is a little hard to pull back, but using the pin technique it's not so bad.
-CO2 canisters are the most expensive part to this grenade...but it is well worth it.
-The rings have a tendency to loosen up when you toss the grenade and then fling off when it explodes. Try using the orange rings so you can find them easier.
-Having to wait for your friends to clean out their pants after one goes off by them.