The present invention relates to a stapler apparatus, comprising a stapler having a proximal end, a distal end and a longitudinal axis, the stapler further comprising a trigger, an anvil docking pin aligned substantially parallel with the longitudinal axis of the stapler, and a stapling means, the anvil docking pin and stapling means being at the distal end of the stapler, and a detachable anvil, comprising an anvil head and an anvil shaft, wherein the anvil shaft is adapted to receive the anvil docking pin and operation of the trigger causes the stapling means to be actuated, characterised in that the length of the anvil shaft is at least 4 cm. The present invention also relates to a method of forming an anastomosis between two surfaces using the stapler apparatus of the invention and a method of forming a stoma trephine in a subject using the stapler apparatus of the invention. The present invention further relates to the use of the stapler apparatus or anvil for a stapler apparatus in such methods and a kit of parts comprising the stapler apparatus of the invention and additional components.