Exhibit 1

JOINT FILING AGREEMENT

Each of the undersigned hereby agrees that this Schedule 13D Amendment No. 2 is being filed with the Securities and Exchange Commission on behalf of each of the undersigned pursuant to Rule 13d-1(k) promulgated under the Securities Exchange Act of 1934, as amended.

Dated: February 9, 2015
	Draper Fisher Jurvetson Fund IX, L.P.
	By: Draper Fisher Jurvetson Fund IX Partners, L.P. (general partner)
	By: DFJ Fund IX, Ltd., its general partner
	By:	/s/ Timothy C. Draper
	Name:	Timothy C. Draper
	Title:	Managing Director
	Draper Fisher Jurvetson Fund IX Partners, L.P.
	By: DFJ Fund IX, Ltd., its general partner
	By:	/s/ Timothy C. Draper
	Name:	Timothy C. Draper
	Title:	Managing Director
	DFJ Fund IX, Ltd.
	By:	/s/ Timothy C. Draper
	Name:	Timothy C. Draper
	Title:	Managing Director
	Draper Fisher Jurvetson Partners IX, LLC
	By:	/s/ Timothy C. Draper
	Name:	Timothy C. Draper
	Title:	Managing Member

CUSIP NUMBER  83416T100 13D Page 2 of 7 Pages

Draper Fisher Jurvetson Fund X, L.P.
By: Draper Fisher Jurvetson Fund X Partners, L.P. (general partner)
By: DFJ Fund X, Ltd., its general partner
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	Managing Director
Draper Fisher Jurvetson Fund X Partners, L.P.
By: DFJ Fund X, Ltd., its general partner
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	Managing Director
DFJ Fund X, Ltd.
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	Managing Director
Draper Fisher Jurvetson Partners X, LLC
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	Managing Member

CUSIP NUMBER  83416T100 13D Page 3 of 7 Pages

Draper Fisher Jurvetson Growth Fund 2006, L.P.
By: Draper Fisher Jurvetson Growth Fund 2006 Partners, L.P. (general partner)
By: DFJ Growth Fund 2006, Ltd., its general partner
By:	/s/ Mark W. Bailey
Name:	Mark W. Bailey
Title:	Director
Draper Fisher Jurvetson Growth Fund 2006 Partners, L.P.
By: DFJ Growth Fund 2006, Ltd., its general partner
By:	/s/ Mark W. Bailey
Name:	Mark W. Bailey
Title:	Director
DFJ Growth Fund 2006, Ltd.
By:	/s/ Mark W. Bailey
Name:	Mark W. Bailey
Title:	Director
Draper Fisher Jurvetson Partners Growth Fund 2006, LLC
By:	/s/ Mark W. Bailey
Name:	Mark W. Bailey
Title:	Authorized Member

CUSIP NUMBER  83416T100 13D Page 4 of 7 Pages

Draper Associates, L.P.
By: Draper Associates, Inc. (its general partner)
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	President
Draper Associates, Inc.
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	President
Draper Associates Riskmasters Fund, LLC
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	Manager
Draper Associates Riskmasters Fund III, LLC
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	Managing Member
JABE, LLC
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	Managing Member

CUSIP NUMBER  83416T100 13D Page 5 of 7 Pages

The Draper Foundation
By:	/s/ Timothy C. Draper
Name:	Timothy C. Draper
Title:	President
/s/ Timothy C. Draper
Timothy C. Draper
/s/ John H. N. Fisher
John H. N. Fisher
John H.N. Fisher and Jennifer Caldwell Living Trust dated 1/7/00, as amended and restated on 3/27/08
By:	/s/ John H. N. Fisher
Name:	John H. N. Fisher
Title:	Trustee
The Fisher/Caldwell 2012 Irrevocable Children’s Trust U/A/D 6-12-12
By:	/s/ John H. N. Fisher
Name:	John H. N. Fisher
Title:	Trustee
JHNF Investment LLC
By:	/s/ John H. N. Fisher
Name:	John H. N. Fisher
Title:	Managing Member
/s/ Stephen T. Jurvetson
Stephen T. Jurvetson

CUSIP NUMBER  83416T100 13D Page 6 of 7 Pages

The Steve and Karla Jurvetson Living Trust dated 8/27/02
By:	/s/ Stephen T. Jurvetson
Name:	Stephen T. Jurvetson
Title:	Trustee
/s/ Barry M. Schuler
Barry M. Schuler
The Barry Martin Schuler and Tracy Strong Schuler 1998 Trust
By:	/s/ Barry M. Schuler
Name:	Barry M. Schuler
Title:	Trustee
The Meteor Group, LLC
By:	/s/ Barry M. Schuler
Name:	Barry M. Schuler
Title:	Managing Member
/s/ Mark W. Bailey
Mark W. Bailey
The Bailey Family Trust UAD 8/31/10
By:	/s/ Mark W. Bailey
Name:	Mark W. Bailey
Title:	Trustee
/s/ Randy Glein
Randy Glein

CUSIP NUMBER  83416T100 13D Page 7 of 7 Pages

The Glein Family Trust UAD 4/30/13
By:	/s/ Randy Glein
Name:	Randy Glein
Title:	Trustee