13D Filing: Discovery Group I, LLC and Entellus Medical Inc (ENTL)

Names of Reporting Persons.

Discovery Equity Partners, L.P.

Source of Funds (See Instructions)

WC

Citizenship or Place of Organization

Illinois

Sole Voting Power

None.

Sole Dispositive Power

None.

Shared Dispositive Power

2,163,929

Aggregate Amount Beneficially Owned by Each Reporting
Person

2,163,929

Names of Reporting Persons.

Discovery Group I, LLC

Source of Funds (See Instructions)

AF

Citizenship or Place of Organization

Delaware

Sole Voting Power

None.

Shared Voting Power

2,163,929

Sole Dispositive Power

None.

Shared Dispositive Power

2,163,929

Aggregate Amount Beneficially Owned by Each Reporting
Person

2,163,929

Percent of Class Represented by Amount in Row (11)

8.5%

Type of Reporting Person (See Instructions)

IA

Item 3 of the Schedule 13D is
hereby amended to read in its entirety as follows:

The total purchase price for the
2,163,929 shares of Common Stock beneficially owned by the Reporting Persons as of August 21, 2017 was approximately $31,973,385.
The source of such funds was the assets of Discovery Equity Partners, including proceeds of margin loans under margin
loan facilities maintained in the ordinary course of business by Discovery Equity Partners with a broker on customary
terms and conditions. Discovery Equity Partners is the legal owner of all of the Common Stock beneficially owned by Discovery
Group.

Item 5 of the Schedule 13D is
hereby amended to read in its entirety as follows:

The information concerning percentages
of ownership set forth below is based on 25,371,181 shares of Common Stock outstanding as of July 28, 2017 in the Company’s
Quarterly Report on Form 10-Q for the quarter ended June 30, 2017.

Discovery Equity Partners beneficially
owns 2,163,929 shares of Common Stock as of August 21, 2017, which represents 8.5% of the outstanding Common Stock.

Discovery Group beneficially owns
2,163,929 shares of Common Stock as of August 21, 2017, which represents 8.5% of the outstanding Common Stock.

Discovery Group is the investment
manager of Discovery Equity Partners.   Discovery Group exercises ultimate voting and dispositive power of the
securities held by Discovery Equity Partners. As a consequence, Discovery Group may be deemed to share beneficial ownership
of all of the shares of Common Stock owned by Discovery Equity Partners. Voting and disposition decisions at Discovery
Group with respect to the investment of such securities are made by a five-person investment committee (the “Committee”)
which makes such investment decisions by majority vote. No member of the Committee may act individually to vote or sell
shares of Common Stock held by Discovery Equity Partners, nor does any such member have a veto right concerning the vote
or sale of any such common stock. Accordingly, no individual member of the Committee is deemed to beneficially own, and
each individual member of the Committee expressly disclaims beneficial ownership of, within the meaning of Rule 13d-3,
any shares of Common Stock held by Discovery Equity Partners solely by virtue of the fact that he or she is a member of
the Committee.

The transactions in Common Stock
effected by the Reporting Persons during the past 60 days are set out in Exhibit 1 hereto.

No person other than Discovery
Equity Partners is known to any Reporting Person to have the right to receive or the power to direct the receipt of dividends
from, or the proceeds from the sale of, any of the shares of Common Stock reported herein.

Item 6 of the Schedule 13D is
hereby amended to read in its entirety as follows:

There are no contracts, arrangements,
understandings or relationships (legal or otherwise) between or among any of the Reporting Persons and any other person
with respect to any securities of the Company other than the governing documents of Discovery Group and Discovery Equity
Partners, the margin loan facilities referred to under Item 3 above, the Joint Filing Agreement of the Reporting Persons
with respect to the Schedule 13D that was included as an exhibit thereto, the Joint Filing Agreement of the Reporting
Persons with respect to this Amendment No. 4 included as Exhibit 2 to this Amendment No. 4, and the Power
of Attorney granted by Michael R. Murphy with respect to reports under Section 13 of the Securities Exchange Act of 1934,
as amended, which Power of Attorney is included as Exhibit 3 to this Amendment No. 4.

List of transactions effected
by the Reporting Persons in the Company’s Common Stock during the 60-day period preceding this filing.

Joint
Filing Agreement dated as of August 22, 2017, by and between Discovery Equity Partners and Discovery Group.