... & Service: Features:Circular slide rule side with clear durable cursor,For calculation and conversion of temperature,time,distance,volume,altitude ... 500,000 NM, 1:1000,000 NM, Clear rotating disc for lead pencil plotting, For calculation of heading and groundspeed, wind velocity ... /T, L/C ,Paypal, Western Union or others for negotiation.Samples Offer:Kearing will offer samples at reasonable quantity ...