A container includes a tube (20) having a rim at one end defining an opening and an endcap (40,80) including a channel that is shaped to receive the tube rim. The tube includes at least one latching aperture (30,32) positioned such that when the tube rim is seated in the channel, the latching aperture is contained within the channel. The endcap further includes a latching member (44) that engages the latching aperture when the tube rim is seated in the receiving channel. The latching member includes a sloped surface (62) for deflecting the tube rim to allow the tube rim to be slid into position over the latching member. The endcap further includes a first guide fin assembly (46) on a first side of the latching member and a second guide fin assembly (48) on a second side of the latching member. Each of the first and second guide fin assemblies includes a sloped surface shaped to deflect the tube rim in a direction opposite to the deflection of the tube rim by the latching member when the tube rim is slid into position in the channel, and to maintain the engagement of the latching aperture by the latching member when the tube rim is seated in the channel.