Spherical Densiometer Nautural Finish Convex Model A Description Convex Model A Helpful when establishing spacing standards in forest  thinning and determining light requirements for regeneration. Both models feature a mirror reflector engraved with  a cross-shaped grid of 24 quarter-inch squares to  delineate a plot overhead.Slightly offset convex model when  using so your head does not appear in grid Walnut instrument  case is 3" x 3" Built-in leveling bubble.  Operating instructions included. All items are shipped expedite or via economy shipping as reflected in the listing. Item shipped expedite worldwide via DHL or FedEx or E COM  usually takes 4-7 days for delivery from the date of purchase. Item shipped via economy shipping takes 10-25 days delivery time and the item is not to be considered lost till 6 weeks from the dispatch date. Make sure you provide correct address with land marks nearby  to avoid unnecessary delay in delivery on account of insufficient of incorrect address We do believe in PayPal for payment