The units' rugged probes mean there are no parts to wear out. Neither solids nor slurries build up on the switches and they feature one-step, external calibration. The units have LEDs and calibration lights visible through standard window covers. ShieldPoint 300 is a single-point level switch with three-element shielded probes and a 10-A DPDT relay. ShieldPoint 400 is a multipoint switch with several probe options, including a three-element probe, Teflon-coated or bare rods and cables, along with two SPDT 10-A relays. The ShieldPoint 400 has three operating modes: single setpoint, dual setpoint, and pump control. The dual setpoint lets the unit replace two single-point switches for the cost of one.

ASI Instruments Inc., 8570 Katy Freeway, Suite 117, Houston, TX 77024, (800) 245-7056,