The extendable stainless steel probe is one of the most popular gas probes. It collapses down to 1ft overall length and then can be extended to an overall length of 4ft. Optional water/dust stop filter to protect the probe, sample line and pump from debris is available. Sampling probes are available in many sizes and types to best fit the needs of most any remote sampling requirement. Probes are used in conjunction with industrial scientific sampling pumps or instruments with internal pumps.