Downhill ski poles need to be strong enough for planting turns, light enough so your arms don't tire and flexible enough to withstand hard falls.
If you're a beginner, a good ski pole is any pole that fits. As you become more experienced, you may want to try different materials for a better strength-to-weight ratio.
To fit a pair of ski poles to you, wear shoes or stand in your ski boots. With the poles upside down—grips touching the floor—grab the pole just underneath the basket so that the top of your thumb touches the basket. Your elbow should now be at a 90° angle.
Most poles use a flexible nylon wrist strap. During turns, if you lose your grip, the strap helps keep the pole where you planted it. If you fall, the straps keep your poles with you and not buried in the snow far upslope.
To correctly use wrist straps, your hand should go up through the strap and then the thumb and hand grip over the strap and around the pole.
Tip: When trying on wrist straps in a store, wear ski gloves to ensure they’ll be easy on/off when you’re on the mountain.
Some downhill ski poles now have detachable straps—tearproof loops that click in and out of the grips for fast transitions.
Some poles come with interchangeable baskets or additional baskets can be purchased separately.
Telescoping poles are used by ski mountaineers. These can be lengthened for uphill cross-country climbs or shortened for alpine descents. Some models can also be extended and vertically joined together for use as an avalanche probe.
If you choose telescoping poles, make sure they adjust from waist height for downhill skiing to just above your armpit for effective striding.