Blue smoke grenades by Hallmark Fireworks.

This smoke grenade produces a thick plume of blue smoke for approximately 90 seconds.

Blue Smoke Grenade Specifications
Carton Quantity: 1 x Blue Smoke Grenade 
Approx Duration: 90 Sec
Firework Dimensions: 12cm x 5.5cm
Noise Rating: 0/10
Classification: 1.4G
Safety Distance: Outdoor use only