Abstract: An aid apparatus for level surveying instrument comprises a housing having a receiving chamber therein, two channels at opposite ends of the receiving chamber respectively, a window at one side of the receiving chamber, and a socket opening at the side wall of the housing connecting to receiving chamber via the channel. A controlling member is slidable received in the housing. The controlling member has a movable bar, two seal block disposed at opposite ends of the movable bar for sealing the channel, and a driving member is provided at the housing for driving the controlling to shift, whereby the sealing block being driven by the driving member to seal the channel and to depart from the channel to prevent bubbles formed in liquid.

Abstract: An aid apparatus for level surveying instrument comprises a housing having a receiving chamber therein, two channels at opposite ends of the receiving chamber respectively, a window at one side of the receiving chamber, and a socket opening at the side wall of the housing connecting to receiving chamber via the channel. A controlling member is slidable received in the housing. The controlling member has a movable bar, two seal block disposed at opposite ends of the movable bar for sealing the channel, and a driving member is provided at the housing for driving the controlling to shift, whereby the sealing block being driven by the driving member to seal the channel and to depart from the channel to prevent bubbles formed in liquid.

Abstract: A flap holster with the flap pivotally and removably secured to either side of an ambidextrious holster. The holster inlcudes an opening for the insertion and removal of a handgun and a transverse slot below the opening on each side. The flap is pivotally connected to one side of the holster and extends over the handgun opening. On the underside of the flap, an extensible strip is secured at one end to the flap and includes an end hook at the opposite end to engage one of the transverse slots and secure the flap in place. The extensible strap is preferably captured in a fabric tunnel in the underside of the flap. An inextensible flexible strap is secured at both ends to the extensible strap to limit its extension length to avoid over stressing its elastic properties. The hook is preferably a reverse directed tab dimensioned to slip into the transverse slot allowing the elasticity of the extensible strip to hold the flap closed.