Waterproof the contents of your rucksack cheaply and easily with a heavy-duty plastic refuse bag, sack liner or rolled-down plastic survival bag. OTHER EQUIPMENT A number of battery-operated lantern designs are available, other lanterns burn the same types of fuel that stoves use so the remarks made above also apply here. Take care when lighting the mantle. If hanging a lantern take care that it cannot burn/melt the object that it is suspended from. Glass globes and mantles are very easily broken; carrying your lantern in a padded bag or making a 'cosy' for your globe with a piece of closed-cell foam will help protect it from accidental knocks. Most rucksacks are made from nylon and require little maintenance. Stains and dirt should be removed with plain water and a brush. If necessary use a little mild soap. Do not wash or clean with detergents. Owners of large (50-litre plus) rucksacks can extend the rucksack's useful life by taking note of the following points: When picking up a loaded rucksack, take hold of the top haulage loop (usually found between the two shoulder straps) with one hand, slip the rucksack through one shoulder, release the grip on the haulage loop and slip the other arm through the second shoulder strap. Do not pick up the rucksack up by the shoulder straps which are designed only to support the load. If putting your rucksack onto public transport, place it inside a lockable bag or net to protect straps and belts from being damaged and the contents being tampered with. Take the time to adjust the rucksack to fit you correctly. If your rucksack has an internal frame ask your retailer to demonstrate how this can be shaped to fit your back, and how the rucksack's back system can be fine-tuned to fit you. Periodically re-check that the rucksack is still correctly adjusted. Trekking poles with adjustable shafts should be periodically dismantled and dried thoroughly. Check plastic parts for signs of wear and tear, and replace in good time before the pole loses its telescopic functionality. Compasses should be stored away from metal objects and other compasses. Periodically check your compass against a known direction or other compass to ensure that it is still giving an accurate reading. Small bubbles that form in the housing are quite normal and do not affect the performance of the compass. Compasses that develop large bubbles (more than one-third of the entire housing) can affect the balance of the compass needle and should be returned to your retailer for repair. Electrical and electronic equipment such as walkie-talkies, global positioning systems (GPS), altimeters, satellite and cellular communication devices and avalanche transceivers are standard equipment in the rucksacks of many outdoor users. However, it is important to bear in mind that batteries will eventually fail, as can electronic circuit boards and even satellites. It is vital that users do not rely solely on such items for their safety. The ability to use a map and compass and 'read' potentially avalanche-prone slopes are vital skills that outdoor users should be familiar with.