A holding device and an inserter are provided. The holding device includes a casing providing a cavity including walls, the was encompass a subcutaneous unit. The cavity includes a first side having an outlet opening, the outlet opening before use is covered with a penetrable or removable cover, and a second side comprising a layer having an outer surface and being penetrable, removable or flexible to transfer an impact from outside the layer to the subcutaneous unit. The casing includes a releasable attachment member corresponding to a member on the subcutaneous unit and a needle secured to the casing. An impact towards the outer surface of the layer pushes the subcutaneous unit at least partly out of the casing into a subcutaneous position, when the unit is in the subcutaneous position the releasable attachment member of the casing is released allowing detachment of the unit from the casing.