Seiler Instrument & Manufacturing Company was awarded the contract for the M138 Elbow Telescope (NSN: 1240-01-515-8264, P/N: 13005104) by DLA Land Warren in Warren, Michigan.
The M138 Elbow Telescope is the direct fire telescope used on the M777 and M198 Howitzer. It is an 8-power, 8-degree field of view instrument. An elevation reticle is provided for direct fire and a cursor reticle provides for range settings on the mil scale reticle. The reticles are illuminated by battery powered LEDs.