A special handle assembly in the 840 Series Resistance/Resistivity Probes allows quick connects and disconnects when making resistance measurements. Although designed for the company's 800 Series meters, they can be used with other meters. Included in the series are four different probes: the 841, a 1/2" diameter pin style; the 842, a 1" diameter style; the 844, a 1/2" point-to-point pin style with conductive rubber electrodes; and the 845, a 2.5" diameter flooring/workstation probe. The 848 handle assembly has a machined Delrin housing, BNC connection, and a 3-foot, two-conductor shielded Teflon cable terminated with banana plugs. Models 841, 842 and 844 contain an array of gold-plated spring loaded electrodes that allow a user to measure small, flat, uneven and curved surfaces. Probe prices range from $145 to $325. ELECTRO-TECH SYSTEMS INC., Glenside, PA. (215) 887-2196.