Geoprobe.com describes SP16 Groundwater Sampler:
The Screen Point 16 groundwater sampling system was the most widely used direct push system for environmental groundwater investigations for several years. Since then, Geoprobe SystemsR has retired the Screen Point 15 system and introduced the Screen Point 16 system (1.6 in. OD screen sheath) which is designed for use under the more powerful GH60 hammer with the heavier 1.5 in. probe rods. These protected screen samplers have only five parts, including the grout plug, plus a few O-rings. Using either of these tools with O-rings on the rod fittings enables you to collect representative groundwater samples from a discrete interval using a bailer, bladder pump, or other device. The length of the screen exposed to the formation can be set from just a few inches to as much as 41-inches to let you select the sampling zone. Additionally, the same screens (Stainless Steel or PVC) can be used in both samplers. The grout plug at the base of the screen makes it possible to conduct bottom-up grouting with bentonite slurries or neat cement using any of the GeoprobeR GS Series grout machines.
The Screen Point 16 Groundwater Samplers are used to collect groundwater samples from unconsolidated materials at depths ranging from near ground surface to over 100 feet below grade. The depth that can be reached with the SP16 samplers is a function of the equipment and methods being used to advance the sampler (manual, static vehicle weight, or percussion probing), the formation being penetrated, and operator experience.