Retractor device for transforming a retrieval device from a deployed position to a delivery position

A kit for retrieving material from a body of a subject, the kit comprising:

• a retrieval device including an elongated shaft and a retrieval assembly coupled to a distal zone of the elongated shaft, wherein—
• the retrieval assembly includes a capture structure and a cover,
• the cover has a first portion coupled to the distal zone of the elongated shaft and a free second portion, and
• the cover has a first position in which the second portion extends proximally from the first portion, a second position in which the second portion extends distally from the first portion, and the cover surrounds at least a portion of the capture structure in the second position;
• and
• a retractor having a tubular structure that defines a channel configured to slidably receive the retrieval device, wherein the tubular structure has a length no greater than twice a length of the capture structure measured along a longitudinal axis, and wherein the retractor is configured to extend distally beyond the capture structure to facilitate moving the cover from the second position after deployment to the first position for redeployment.