Military grade throwable sticky explosive.
The item id for C4 in unturned is 1100. You can use this ID with the commands below to spawn the item, give it to a player or buy it on a modded economy server.
Useable: Throwable
Size_X: 1
Size_Y: 1
Size_Z: 0.3
Player_Damage: 200
Zombie_Damage: 200
Animal_Damage: 200
Barricade_Damage: 100
Structure_Damage: 100
Vehicle_Damage: 200
Resource_Damage: 1500
Object_Damage: 750
Range: 10
Explosion: 34
Blueprints: 1
Blueprint_0_Type: Tool
Blueprint_0_Supplies: 4
Blueprint_0_Supply_0_ID: 70
Blueprint_0_Supply_0_Amount: 1
Blueprint_0_Supply_1_ID: 65
Blueprint_0_Supply_1_Amount: 1
Blueprint_0_Supply_2_ID: 73
Blueprint_0_Supply_2_Amount: 1
Blueprint_0_Supply_3_ID: 254
Blueprint_0_Supply_3_Amount: 1
Blueprint_0_Level: 2
Blueprint_0_Skill: Craft
Blueprint_0_Build: 32