3 3/8" Precision 21 & 23 D1 Dwyer

Precision 21 & 23 use the Dwyer mast DM-400 (profile type D1).
This MastGate insert is made for a Feedslot length of 3 3/8" length.
Choice of two materials: White nylon & Gray nylon with glass fill.

DRILLING INSTALLATION for Nipple pin :
The insert sleeve is symmetrical, with two protruding nipple pins. 
Insert a #55 drill bit into each nipple pin's drill guide hole before centering the insert into the feed slot.
Lightly hammer the drill bit to make a mark into the aluminum channel. 
Remove the insert to center punch marks and complete the drilling.  Use 1/8" drill bits, then finish drilling holes with a 3/16" drill bit.  Hand twist a larger drill bit in the holes to remove burrs.
Nipple pins of the nylon insert will key into the holes to prevent sliding. 

NOW Refer to the YouTube video for installation.   https://youtu.be/VvgMuhgE8TI

For warranty and support, please register your purchase:
Name, phone number, and email, the part number ordered, sailboat's year, make & model to:
TomLuQue@gmail.com
design / pg768A D1 DM400 Precision 21 23 V100.1