“Telelin” make Mc-leod gauges measures absolute vacuum in its very last stages. 
                                
                                Model No : MG-6 Portable Mc-leod gauge, with stand   & 1 st fill Mercury. 
                                
                                The vacustate suitable for measurement of   vacuum in the range : 10 mm. to 10-3mm of Hg. (i.e. 10 mm. to 0.001 torr) with   stand & 1 st Mercury. This gauge avoids use of a movable reservoir of   mercury and also requires only about 14 cc. of mercury for first filling. The   total size of this gauge is about 9” x 6”. Metallic stand with Rotating   arrangement & 1 st fill mercury is provided. 
                                
                                WORKING OF THE   GAUGES : 
                                
                                The system of which vacuum is to be measured, is   connected by flexible rubber tubing to nozzle on the back centre of gauge at A.   Gauge is in Horizontal position-1 initially. To take vacuum reading, gauge is to   be rotated in the vertical position-2. Mercury runs out of the container B,   compressing the residual air or gas. contained within region C & D, to short   length of capillary tube C & E. By arranging that the level in the   comparison capillary F is opposite the end of the graduated capillary C & E,   slight adjustment of gauge above the vertical axis is needed to adjust the   mercury level correctly. the Reading in tube C-E is absolute Vacuum in mm of Hg   in your line. 
                                
                                Gauge is portable & so one gauge can be used to   counter check absolute vacuum at different places. Very help full to know that   permanently mounted Dial Type Pressure gauge or U-Tube high vacuum manometer or   any other gauge is giving correct reading or needs maintenance &   re-calibration. scale is expanded from 1.0 to .001 toor and so minute reading in   very last stages becomes passable. 
                                
                                Other vacuum measuring manometer   available with us are : a) U-Tube Absolute High vacuum manometer with Attached   Catchpot, measure vacuum in last stages from 660 mm to 760 mm Hg., in stapes of   1mm Hg. b) Full range vacuum manometer, one end open to atmosphere range 0 to   760 mm Hg. c) Condenser Vacuum gauge with Attached Catchpot. Lighting   arrangement is optional.