Backrest for a scuba diver with adjustable shoulder straps integrated with a lumbar strap

A backrest for a scuba diver, the backrest comprising:

• a shaped plate supporting at least one air cylinder, said shaped plate comprising a lower right slide-through element and a lower left slide-through element, said lower right slide-through element comprising a single aperture and said lower left slide-through element comprising a single aperture;
• a right strap fixed at a top of said shaped plate, the right strap comprising an upper right portion configured to fit around a right shoulder of the scuba diver, a lower right portion configured to fit around an abdomen of the scuba diver, and a right adjustment block between said upper right portion and said lower right portion, the right adjustment block being a monolithic piece and comprising:
• a first pin comprising one or more protuberances for engaging in a blocked position with a first loop of one end of said upper right portion of said right strap,
• a second pin comprising one or more protuberances for engaging in a blocked position with a second loop of one end of said lower right portion of said right strap,
• a clamp element clamping said lower right portion of said right strap to block the sliding of said end of said lower right portion of said right strap around said second pin, and
• a handgrip element actuating said clamp element between a position of blocking and a position of unblocking the sliding of said end of said lower right portion of said right strap around said second pin;
• and
• a left strap fixed at the top of said shaped plate, the left strap comprising an upper left portion configured to fit around a left shoulder of the scuba diver, a lower left portion configured to fit around the abdomen of the scuba diver, and a left adjustment block between said upper left portion and said lower left portion, the left adjustment block being a monolithic piece and comprising:
• a first pin comprising one or more protuberances for engaging in a blocked position with a first loop of one end of said upper left portion of said left strap,
• a second pin comprising one or more protuberances for engaging in a blocked position with a second loop of one end of said lower left portion of said left strap,
• a clamp element clamping said lower left portion of said left strap to block the sliding of said end of said lower left portion of said left strap around said second pin, and
• a handgrip element actuating said clamp element between a position of blocking and a position of unblocking the sliding of said end of said lower left portion of said left strap around said second pin,
• wherein said lower right portion of said right strap passes through said single aperture of the lower right slide-through element of said shaped plate only once and said lower left portion of said left strap passes through said single aperture of the lower left slide-through element of said shaped plate only once to secure the backrest in a first position, the first position being a dorsal position;
• and wherein said single aperture of the lower right slide-through element comprises a first plurality of protrusions directed inward toward said lower right portion of said right strap and said single aperture of the lower left slide-through element comprises a second plurality of protrusions directed inward toward said lower left portion of said left strap.