The 2 m subtense bar from Zeiss Jena is a 2 piece light metal tube which you can stuck together via s screw flange. The ends of the tube have targets at exactly 2 m separation. They can also be illuminated electricaly with an illumination set. You will receive also the illumination set (green color), but accumulator (storage battery) is unfortunately NOT a part of the set. The small lamps were normally equipped with small 2,5V 0,2A bulbs. Inside each half of the rod there is an invar bar for temperature compensation. Invar (nickel-iron alloy) is unique in its resistance to the temperature changes, so unlike other metals it will not expand or contract. Subtense bar is also called parallactic bar, because it was used as a base by measuring parallactic angle with precision theodolites, like for example THEO 010. Once all is set up, observer will measure the angle from his position to each end of the 2m markings on the subtense bar, do some calculations and he will get the distance from the observer to the centre point of the bar. Subtense bar was made in the early 70's. Color of the bar is grey. MPN: 42658. Conditon: USED. It is in fully operational condition and nicely preserved (some scratches or small patches with peeled off color are present). Wooden transport box is in good condition too. Accessories: illumination set is probably never used (it is green painted), but the canvas pouch with leather attachment is clearly used. Tribrach is most likely unused and plumb bob is in excellent condition too. Other carrying bags (for staff and for tribrach) are in very nice, like new condition. Of course you will receive also the original distance table in 4 languages. Please take a closer look at the detailed gallery pictures of the relevant set. Please also note, that the wooden tripod in the picture no.4 is NOT for sale and was used for full display purposes only!