http://www.bcbin.com/Default.aspx?cid=17

Location Marker Balloon
CK409

Developed for the UK MOD, the BCB location marker balloon is a bespoke product designed to meet exacting military requirements.The balloon's primary function is as a visual beacon for helicopter pilots extracting personnel from dense jungle. The balloon floats above the canopy creating a radar signature and can be fitted with light discs (see below) for low light / night time operations. The smallest and lightest product of its kind available today.

136 litre radar reflective balloon
75m (250ft) teather line
Flow regulated valve
Can be operated in minutes
Non-flammable / non-toxic helium gas
Vacuum sealed
Length: 35.1cm (13.5")
Max diameter: 8.06cm (3.1")
Max operation time: 120 hours
Weight: 1.6 Kg (3.5lb)
NSN: 4240-99-366-5580