According to the charge sheet of the case, Maulana Tajuddin, a leader of banned militant outfit Harkat-ul-Jihad Bangladesh (Huji), supplied 15 grenades. Among the bombs, 14 were thrown at the AL rally on August 21, 2004. 3 were found unexploded and another one was found near the old central jail in Dhaka.
Here are some details on the grenade
Type: Hand grenade
Action: Time fuse explosive
Origin: Arges, Austria
Made in: China
Weight: over 1kg
Size: Largest in its production line
Splinters: Around 36,000 per granade
Blast radius: Detonation can propel shrapnel over 90 metres.
Damage: Inflicts massive damage to soft targets within blast radius.
Source: Military Factory