Strap for diving face mask
A strap for diving face mask includes an upper branched sub-section and a lower branched sub-section forming together a loop section in a middle zone of the strap as viewed lengthwise. The upper branched sub-section has a circumferential length larger than a circumferential length of the lower branched sub-section and preferably right and left halves of the strap are sloped toward the side of the lower branched sub-section.
1. A strap for diving face mask having a lengthwise axis extending lengthwise, a widthwise axis extending widthwise, an inner side facing a wearer's head, an outer side facing away from the wearer's head, a loop section defined in a middle zone thereof as viewed lengthwise and lateral sections extending from both sides of said loop section lengthwise, wherein said loop section comprises an upper branched sub-section and a lower branched sub-section which are divided by said lengthwise axis while said loop section is bilaterally symmetric with respect to a second lengthwise axis;
said upper branched sub-section has a circumferential length larger than a circumferential length of said lower branched sub-section;
wherein right and left halves of said strap divided by said widthwise axis slope toward the side of said lower branched sub-section.
2. The strap as defined by claim 1 , wherein said inner side facing the wearer's head is concavely curved in said loop section as viewed in a sectional view taken widthwise.
3. The strap as defined by claim 1 , wherein said upper branched sub-section and said lower branched sub-section are provided with depressed thinner regions.
4. The strap as defined by claim 1 , wherein opposite ends of said loop section lengthwise are provided with depressed thinner regions.
5. The strap as defined by claim 1 , wherein said strap is elastically stretchable at least lengthwise of lengthwise and widthwise.
6. A strap for diving face mask having a lengthwise axis extending lengthwise, a widthwise axis extending widthwise, an inner side facing a wearer's head, an outer side facing away from the wearer's head, a loop section defined in a middle zone thereof as viewed lengthwise and lateral sections extending from both sides of said loop section lengthwise, wherein said loop section comprises an upper branched sub-section and a lower branched sub-section which are divided by said lengthwise axis while said loop section is bilaterally symmetric with respect to a second lengthwise axis;
said upper branched sub-section has a circumferential length larger than a circumferential length of said lower branched sub-section;
wherein said inner side facing the wearer's head is concavely curved in said loop section as viewed in a sectional view taken widthwise.
7. The strap as defined by claim 6 , wherein said upper branched sub-section and said lower branched sub-section are provided with depressed thinner regions.
8. The strap as defined by claim 6 , wherein opposite ends of said loop section lengthwise are provided with depressed thinner regions.
9. The strap as defined by claim 6 , wherein said strap is elastically stretchable at least lengthwise of lengthwise and widthwise.
10. A strap for diving face mask having a lengthwise axis extending lengthwise, a widthwise axis extending widthwise, an inner side facing a wearer's head, an outer side facing away from the wearer's head, a loop section defined in a middle zone thereof as viewed lengthwise and lateral sections extending from both sides of said loop section lengthwise, wherein said loop section comprises an upper branched sub-section and a lower branched sub-section which are divided by said lengthwise axis while said loop section is bilaterally symmetric with respect to a second lengthwise axis;
said upper branched sub-section has a circumferential length larger than a circumferential length of said lower branched sub-section;
wherein said upper branched sub-section and said lower branched sub-section are provided with depressed thinner regions.
11. The strap as defined by claim 10 , wherein opposite ends of said loop section lengthwise are provided with depressed thinner regions.
12. The strap as defined by claim 10 , wherein said strap is elastically stretchable at least lengthwise of lengthwise and widthwise.
13. A strap for diving face mask having a lengthwise axis extending lengthwise, a widthwise axis extending widthwise, an inner side facing a wearer's head, an outer side facing away from the wearer's head, a loop section defined in a middle zone thereof as viewed lengthwise and lateral sections extending from both sides of said loop section lengthwise, wherein said loop section comprises an upper branched sub-section and a lower branched sub-section which are divided by said lengthwise axis while said loop section is bilaterally symmetric with respect to a second lengthwise axis;
said upper branched sub-section has a circumferential length larger than a circumferential length of said lower branched sub-section;
wherein opposite ends of said loop section lengthwise are provided with depressed thinner regions.
14. The strap as defined by claim 13 , wherein said strap is elastically stretchable at least lengthwise of lengthwise and widthwise.